Partner Choice and Context‐Dependent Sex Differences in Rat Rough‐and‐Tumble Play
Open accessAbstract
Rough‐and‐tumble play (RTP) is the form of play most often observed in juvenile mammals. In rats, RTP typically consists of competing for access to the partner's nape, with both sex and social contexts influencing its frequency and structure. Although most studies employ dyadic tests, this design limits partner choice. Here, we investigated sex differences in partner preference and play frequency in Wistar rats using a group play paradigm. Juvenile rats were tested in mixed‐sex and same‐sex triads, allowing individuals to select partners. We measured playful nape attacks, defensive responses, and the distribution of play across partners. Results revealed that both sexes formed partner preferences, but only males exhibited sex‐based preferences, directing significantly more playful attacks toward females than males. Female rats showed no group‐level sex preference, though most individuals displayed consistent preferences for one partner, often, but not exclusively, for the male partner. Importantly, females initiated fewer nape attacks than males in mixed‐sex groups, but this sex difference disappeared in all‐female groups, where females initiated playful attacks at levels comparable to males. Thus, sex differences in RTP frequency were context dependent, emerging only when females were tested alongside males. These findings demonstrate two distinct forms of sex differences in the play of rats: partner choice and play frequency. Whereas males preferentially engage with females, females appear more flexible, forming idiosyncratic preferences independent of the partner's sex. Moreover, female play initiation is particularly sensitive to social context, highlighting the importance of group‐based testing for understanding naturalistic social decision‐making.
AI snapshot
Written from the paper’s full text.
TL;DR
In mixed-sex triads, male Wistar rats preferred female partners and initiated more nape attacks than females, whereas females showed no group-level sex preference and formed weaker partner preferences. Female play initiation was context-dependent: females played less than males in mixed-sex groups but matched male levels in all-female groups.
Key findings
- Both sexes formed partner preferences in mixed-sex triads, but only males showed a sex-based preference: males directed more nape attacks toward female than male partners (paired t₇ = 5.444, p = 0.0010; proportion one-sample t₇ = 4.769, p = 0.0020), with 7/8 males preferring females.
- Focal females in mixed-sex groups showed no group-level preference for either sex (number: t₇ = 1.249, p = 0.251; proportion: t₇ = 1.171, p = 0.270), but did prefer one partner over the other (t₇ = 6.751, p = 0.0003); 6/8 preferred the male partner and 2 preferred the same-sex partner.
- In all-female triads, females formed a preference for one female (t₇ = 3.227, p = 0.015), but this preference was weaker than in mixed-sex groups (61% vs. 55% of attacks to preferred partner; paired t₇ = 3.273, p = 0.014).
- Sex differences in play frequency were context-dependent: mixed-effects model F₁.₈₇₁,₁₃.₀₉ = 8.363, p = 0.0051; females in mixed-sex groups played less than in all-female groups (p = 0.031), and males played more than females in mixed-sex groups (p = 0.016), but this difference disappeared when females played in same-sex groups.
Methods
- Wistar rats (16 females, 10 males) were tested in a group play paradigm using unfamiliar, unrelated partners from different litters. Triads were focal female with one female and one male, focal male with one female and one male, or focal female with two females; eight unique trios were formed per condition, and no all-male triad was included.
- After habituation on PND28–29, rats were socially isolated for 2.5 h and then tested for 20 min on PND30 and PND32 under red light. Videos were scored for playful nape attacks, partner identity, and defensive responses including pins.
- Analyses used Shapiro–Wilk normality tests, paired t-tests for attack frequency and pin proportion, one-sample t-tests for >50% partner-directed attack proportions, and mixed-effects models with Bonferroni correction for sex differences in total play frequency.
Limitations
- Stated by the authors: sample size was small; 6/8 females preferred the opposite sex, and a larger sample would likely make this significant, but would not explain why some females preferred males and others females. One male preferred the same-sex partner.
- Stated by the authors: blinding was not feasible because by PND28 rats show clear sexual dimorphism, making sex-based group assignment apparent during video scoring.
- Stated by the authors: analyses focused on play initiated by focal animals and did not quantify initiation by non-focal partners, so changes in motivation cannot be distinguished from changes in opportunity; additionally, no all-male triad was included, and sample sizes were based on prior studies rather than an a priori power analysis.
Model-written summary. Check it against the paper before relying on it.
Integrity signals
Registry
Cites
Statistics
Claims the paper makes
10 of 38 cited sources checked · 2 supported · 2 flagged · accuracy not yet measured
- Premisecitation
It is the female rats who are sensitive to mixed-sex housing.
“Interestingly, it seems that it is the female rats who are sensitive to mixed‐sex housing.”
Quote in the paperSubstantial claim1 of 3 sources checked- cites Achterberg et al. 2024
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
- cites Argue and McCarthy 2015 source
The Methods (Animals; page not provided) say the rats were housed in same-sex groups, so this study did not test mixed-sex housing. The Discussion (page not provided) reports a prior finding that cagemates’ sex affected males’ social behavior, with no effect observed in females—the opposite of the attributed claim. (LLM, conf=0.88)
Checked by a reasoning model — may be wrong.
Experimental — accuracy not yet measured - cites Northcutt and Nwankwo 2018 source
- Premisecitation
Males play more when partnered with females than when with males, when playing in dyads.
“Given that males play more when partnered with females than when with males, when playing in dyads, and that females play at similar levels regardless of the sex of the partner (Argue and McCarthy 2015)”
Quote in the paperSubstantial claim1 of 1 sources checked- cites Argue and McCarthy 2015 source
The Results section, “Play partner affected the time spent engaged in play,” reports that male–male pairs spent more time playing than mixed-sex pairs—the opposite of the claim about males. The Results section on total frequency finds no significant change for males or females by partner sex; it supports the female comparison for frequency, but not the asserted increase for males. (LLM, conf=0.90)
Checked by a reasoning model — may be wrong.
Experimental — accuracy not yet measured
- Premisecitation
When reared in mixed-sex groups, females typically play less than males, even when tested in same-sex pairs.
“When reared in mixed‐sex groups, females typically play less than males, even when tested in same‐sex pairs.”
Quote in the paperSubstantial claim1 of 3 sources checked- cites Achterberg et al. 2024
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
- cites Argue and McCarthy 2015 source
The Results section reports that males played more frequently than females even in same-sex test pairs. But the Discussion says the animals were housed in same-sex groups, so this study does not establish the claim for rats reared in mixed-sex groups. No page numbers are available in our copy. (LLM, conf=0.88)
Experimental — accuracy not yet measured - cites Northcutt and Nwankwo 2018 source
- Premisecitation
Juvenile female rats are more sensitive to the familiarity of their play partner, playing more with familiar individuals over unfamiliar ones.
“Interestingly, juvenile female rats seem to be more sensitive to the familiarity of their play partner, playing more with individuals that they are familiar with over those who are unfamiliar (Argue and McCarthy 2015).”
Quote in the paperNot a substantial claim1 of 1 sources checked- cites Argue and McCarthy 2015 source
The Discussion reports less play when juvenile females were paired with a novel female rather than a familiar partner, supporting a familiarity effect. It also says this did not occur with a novel male partner, so the claim is too broad without the female-female qualification. (LLM, conf=0.88)
Experimental — accuracy not yet measured
- Premisecitation
Females play at similar levels regardless of the sex of the partner.
“Given that males play more when partnered with females than when with males, when playing in dyads, and that females play at similar levels regardless of the sex of the partner (Argue and McCarthy 2015)”
Quote in the paperSubstantial claim1 of 1 sources checked- cites Argue and McCarthy 2015 source
The Results report that females’ total frequency of play did not change significantly with partner sex, supporting the claim when 'levels' means frequency. The Discussion says time spent playing increased when females were paired with males, so the broader claim that their play was similar regardless of partner sex is not fully supported. (LLM, conf=0.86)
Experimental — accuracy not yet measured
- Findingown data
The strength of partner preference in focal females was weaker in all-female triads (55% of attacks to preferred partner) than in mixed-sex triads (61% of attacks to preferred partner).
“However, when compared with the preference strength for the preferred partner in mixed‐sex groups (whether male or female), we found that female rats playing in all‐female groups had weaker partner preferences for the preferred partner in the mixed‐sex groups (paired t‐test: t 7 = 3.273, p = 0.014).”
- Also stated in: § Context‐Dependent Sex Differences · plain
“When playing in mixed‐sex groups, the focal female rats directed 61% to their preferred partner, whereas during same‐sex play, they directed 55% of their play toward their preferred partner (Figure 3a).”
Quote in the paperSubstantial claim - Also stated in: § Context‐Dependent Sex Differences · plain
- Findingown data
Among focal males in mixed-sex triads, 7 of 8 preferred to play with the female partner over the male partner.
“Seven of the eight males preferred to play with females over males.”
Quote in the paperSubstantial claim - Findingown data
In mixed-sex triads, focal female rats did not show a sex-based preference, directing similar numbers and proportions of nape attacks toward male and female partners.
“Female rats showed no group‐level sex preference, though most individuals displayed consistent preferences for one partner, often, but not exclusively, for the male partner.”
- Also stated in: § Partner Preferences · plain
“The number of nape attacks female rats directed towards male and female partners in mixed‐sex groups (Figure 1a) did not differ significantly (paired t‐test: t 7 = 1.249, p = 0.251).”
- Also stated in: § Partner Preferences · hedged
“Similarly, the proportion of times females were attacked was not greater than 50%, suggesting that there was no difference in the proportion of attacks directed toward either sex (one‐sample t‐test: t 7 = 1.171, p = 0.270) (Figure 1b).”
Quote in the paperSubstantial claim - Also stated in: § Partner Preferences · plain
- Findingown data
In mixed-sex triads, focal females initiated significantly fewer nape attacks than focal males.
“females initiated fewer nape attacks than males in mixed‐sex groups”
- Also stated in: § Context‐Dependent Sex Differences · plain
“When the total number of nape attacks was compared (Figure 3b), we found males and females did not initiate the same amount of play (mixed‐effects model: F 1.871,13.09 = 8.363, p = 0.0051).”
- Also stated in: § Context‐Dependent Sex Differences · plain
“Post hoc comparisons revealed that the females in mixed‐sex groups played significantly less than when they were in all‐female groups (p = 0.031), whereas males played more than females in such groups (p = 0.016).”
Quote in the paperSubstantial claim- Rests on an assumption: The 2.5 h social isolation period increases play motivation without altering partner preferences.
- Also stated in: § Context‐Dependent Sex Differences · plain
- Findingown data
In all-female triads, focal female rats formed a significant preference for one of the two female partners, playing with one more than expected by chance.
“When playing in same‐sex groups, we found that female rats formed preferences for one of the two females, playing with one partner more than what you would expect by chance (one‐sample t‐test: t 7 = 3.227, p = 0.015).”
Quote in the paperSubstantial claim - Findingown data
Focal females in mixed-sex triads initiated significantly fewer nape attacks than focal females in all-female triads.
“Post hoc comparisons revealed that the females in mixed‐sex groups played significantly less than when they were in all‐female groups (p = 0.031)”
Quote in the paperNot a substantial claim- Rests on an assumption: Repeated testing of the same rats across different group compositions and roles does not substantially affect their play behavior or partner preferences.
- Findingown data
The sex difference in play frequency (males greater than females) was not present when comparing females in all-female triads to males in mixed-sex triads.
“This sex difference in play frequency, however, is not present for females playing in same‐sex groups compared to males playing in mixed‐sex groups (Figure 3b).”
- Also stated in: § Abstract · plain
“this sex difference disappeared in all‐female groups, where females initiated playful attacks at levels comparable to males.”
Quote in the paperSubstantial claim- Rests on an assumption: Repeated testing of the same rats across different group compositions and roles does not substantially affect their play behavior or partner preferences.
- Also stated in: § Abstract · plain
- Findingown data
Our present data show that males can also influence the play of females acutely, even for females housed in same-sex pairs.
“our present data show that males can also influence the play of females acutely, even for females housed in same‐sex pairs.”
Quote in the paperSubstantial claim - Findingown data
Females did form preferences for a given partner.
“though females did form preferences for a given partner.”
Quote in the paperSubstantial claim - Findingown data
Two of the eight females initiated more play with the same-sex partner.
“Given that two of the eight females initiated more play with the same‐sex partner”
Quote in the paperNot a substantial claim - Findingown data
The effect of males initiating more play than females was only observed when females were playing in mixed-sex groups.
“though this effect was only observed when females were playing in mixed‐sex groups.”
Quote in the paperSubstantial claim - Findingown data
6/8 females preferred the opposite sex.
“Given that 6/8 females preferred the opposite sex”
Quote in the paperSubstantial claim - Findingown data
Unlike the males, females playing in groups did not prefer either sex at a group level.
“Unlike the males, we found that females playing in groups did not prefer either sex at a group level”
Quote in the paperSubstantial claim - Findingown data
Like Argue and McCarthy (2015), we found that males play more with females.
“Like Argue and McCarthy (2015), we found that males play more with females.”
Quote in the paperSubstantial claim - Findingown data
Simply being exposed to males during a single play session decreases how much females play.
“Simply being exposed to males during a single play session decreases how much females play.”
Quote in the paperSubstantial claim - Findingown data
In our rats reared in same-sex pairs after weaning, when tested in mixed-sex groups, sex differences in play frequency still emerged.
“Despite our rats being reared in same‐sex pairs after weaning, when tested in mixed‐sex groups, the sex differences in play frequency still emerged”
Quote in the paperSubstantial claim - Findingown data
One of the males preferred the same-sex partner.
“Likewise, one of the males preferred the same‐sex partner.”
Quote in the paperNot a substantial claim - Interpretationown data
Sex differences in RTP frequency in this study were context dependent, emerging only when females were tested alongside males.
“Thus, sex differences in RTP frequency were context dependent, emerging only when females were tested alongside males.”
- Also stated in: § Discussion · hedged
“This suggests that the sex‐difference was due to the social setting and not because the females play less.”
Quote in the paperSubstantial claim- Rests on an assumption: The 2.5 h social isolation period increases play motivation without altering partner preferences.
- Rests on an assumption: Repeated testing of the same rats across different group compositions and roles does not substantially affect their play behavior or partner preferences.
- Also stated in: § Discussion · hedged
- Premisecitation
Most studies of rat RTP use dyadic tests, which limit partner choice.
“However, most studies of RTP employ the “dyadic test,” in which two animals are partnered. These partners are frequently of the same sex (Pellis, Pellis, Burke, et al. 2022; VanRyzin et al. 2020a). The dyadic test has been extremely useful in studying the RTP of rats but does have a limitation.”
Quote in the paperSubstantial claim0 of 2 sources checked- cites Pellis, Pellis, Burke, et al. 2022 source
- cites VanRyzin et al. 2020a
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
- Premisecitation
Neonatal androgens are responsible for sex differences in levels of play initiation by affecting neural circuitry associated with play behavior.
“It is these underlying androgens during the neonatal period that seem to be responsible for the sex differences in levels of play initiation and do so by affecting the neural circuitry associated with play behavior (VanRyzin et al. 2020b).”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites VanRyzin et al. 2020b
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
- Premisecitation
The social context in which rats are reared is particularly important, as sex differences are most apparent when the rats are reared in mixed-sex groups.
“The social context in which rats are reared seems to be particularly important, as sex differences are most apparent when the rats are reared in mixed‐sex groups (for a review, see S. M. Himmler et al. 2016).”
Quote in the paperSubstantial claim0 of 1 sources checked- cites S. M. Himmler et al. 2016 source
- Interpretationown data
Making a choice under mixed-sex conditions is more polarizing than when playing in same-sex groups.
“That is, whether they preferred to play with males or females in the mixed‐sex group, making a choice under mixed‐sex conditions is more polarizing than when playing in same‐sex groups.”
Quote in the paperSubstantial claim - Interpretationown data
Female play initiation is particularly sensitive to social context.
“Moreover, female play initiation is particularly sensitive to social context, highlighting the importance of group‐based testing for understanding naturalistic social decision‐making.”
Quote in the paperSubstantial claim- Rests on an assumption: The 2.5 h social isolation period increases play motivation without altering partner preferences.
- Rests on an assumption: Repeated testing of the same rats across different group compositions and roles does not substantially affect their play behavior or partner preferences.
- Premisecitation
The sex difference in play frequency likely arises from early life hormone-induced changes in the development of relevant brain mechanisms.
“This sex difference likely arises from early life hormone‐induced changes in the development of relevant brain mechanisms (see Pellis 2002 for a review).”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites Pellis 2002 source
- Interpretationown data
Social context is important in the expression of the sex difference in play.
“However, when the females played in same‐sex groups, we found that the sex difference was no longer present, with females playing just as much as their male counterparts, suggesting that social context is important in the expression of the sex difference in play.”
Quote in the paperSubstantial claim- Rests on an assumption: Repeated testing of the same rats across different group compositions and roles does not substantially affect their play behavior or partner preferences.
- Premisecitation
Social isolation increases the motivation of rats to play.
“Given that social isolation increases the motivation of rats to play (Panksepp and Beatty 1980; Pellis et al. 1997), this suggests that the males' preference to play with females is robust, not being masked by a general motivation to play.”
Quote in the paperSubstantial claim0 of 2 sources checked - Interpretationcitation
The results where males prefer females and females do not have a sex preference reflect those of Meaney and Stewart (1981), despite differences in testing procedures.
“Our results, where males prefer females and females do not have a preference for either sex, reflect those of Meaney and Stewart (1981), despite differences in testing procedures.”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites Meaney and Stewart 1981 source
- Interpretationreasoning
Males and females may decide with whom to play using different cues.
“The results from this study suggest that males and females may decide with whom to play using different cues”
Quote in the paperSubstantial claim - Premisecitation
Chronic exposure to males in the home cage can decrease how much females play even when the females are tested in same-sex pairs.
“although chronic exposure to males in the home cage can decrease how much females play even when the females are tested in same‐sex pairs (e.g., Pellis and Pellis 1990)”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites Pellis and Pellis 1990 source
- Interpretationreasoning
Sex differences in playfulness only emerge under certain testing conditions.
“and that sex differences in playfulness only emerge under certain testing conditions.”
Quote in the paperSubstantial claim - Study design and conductnone given
The females in this study did not have a choice over individuals who are familiar versus those who are unfamiliar.
“Although the females in this study did not have a choice over individuals who are familiar versus those who are unfamiliar”
Quote in the paperNot a substantial claim - Premisecitation
When tested in groups with individuals of varying familiarity, males prefer to play with novel, unfamiliar partners over familiar cage mates.
“When tested in groups, where the individuals are of varying familiarity (i.e., cage mate, individual on the other side of a clear and perforated divider, or a complete stranger), males prefer to play with novel, unfamiliar partners over familiar cage mates (Ham and Pellis 2023).”
Quote in the paperSubstantial claim0 of 1 sources checked- cites Ham and Pellis 2023 source
- May combine two claims. 19
- The quote only partly states this claim. 2
- Classified as probably not a substantial claim. 6
May combine two claims.
PremisecitationSex differences in the amount of RTP initiated vary across studies, with some reporting males play more and others finding no significant differences.
“In addition to sex differences in partner preferences, rats also show sex differences in the amount of RTP initiated. However, this varies from study to study, with some reporting that males play more (Argue and McCarthy 2015; Olioff and Stewart 1978) and others do not find significant differences between sexes (Orsucci et al. 2025; Stark et al. 2021).”
Quote in the paperNot a substantial claim2 of 3 sources checkedMay combine two claims.
PremisecitationIn natural settings, juvenile rats have access to many potential partners of both sexes, so they have choice with whom to play, unlike laboratory rats tested in pairs.
“In the wild, as juvenile rats age, they would not only have access to their littermates, but also peers from nearby litters, and therefore many potential partners of both sexes (Calhoun 1963; Schweinfurth 2020). Thus, in natural settings, rats would have choice with whom to play, a choice that laboratory rats tested in pairs are not afforded.”
Quote in the paperSubstantial claim2 of 2 sources checked- cites Calhoun 1963 source
The burrow description (p. 18) reports young from a first litter sharing a burrow with a second litter, and another description reports five litters of varying ages in one burrow. These observations support access to peers beyond littermates in a naturalistic setting. Our copy does not establish that juveniles could choose play partners of both sexes or make the comparison with laboratory rats tested in pairs. (LLM, conf=0.82)
Experimental — accuracy not yet measured - cites Schweinfurth 2020 source
The Play behaviour section says young wild rats play and identifies play fighting in both sexes. The Research in Biomedicine section says wild rats interact with far more group members than captive rats. The copy does not establish that juveniles encounter peers from nearby litters or choose among play partners, nor does it specifically compare that choice with laboratory rats tested in pairs. (LLM, conf=0.82)
Experimental — accuracy not yet measured
May combine two claims.
PremisecitationA reduction in female play, and not a change in the frequency of male play, drives the sex effect.
“Indeed, it is a reduction in female play, and not a change in the frequency of male play, that drives the sex effect”
Quote in the paperSubstantial claim1 of 3 sources checked- cites Achterberg et al. 2024
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
- cites Argue and McCarthy 2015 source
The Results (Fig. 1c; page unavailable) report reduced play when females were paired with novel female partners, and the Discussion says this did not occur in males paired with novel partners. But the paper does not say that this female-specific response drives the overall sex difference in play; that reduction was limited to the novel-partner condition. (LLM, conf=0.84)
Experimental — accuracy not yet measured - cites Northcutt and Nwankwo 2018 source
May combine two claims.
Findingown dataAmong focal females in mixed-sex triads, most (6 of 8) preferred to play with the male partner, while 2 preferred the female partner.
“Most females preferred to play with males (n = 6); however, two preferred same‐sex partners (Figure 1b).”
Quote in the paperSubstantial claimMay combine two claims. The quote only partly states this claim.
Findingown dataIn mixed-sex triads, both female and male focal rats formed a significant preference for one partner over the other, playing with one partner more than expected by chance.
“Results revealed that both sexes formed partner preferences, but only males exhibited sex‐based preferences, directing significantly more playful attacks toward females than males.”
- Also stated in: § Partner Preferences · plain
“Despite not preferring a particular sex, female rats did show a significant preference for one of the partners playing with one partner significantly more than what you would expect by chance (one‐sample t‐test: t 7 = 6.751, p = 0.0003).”
Quote in the paperSubstantial claim- Also stated in: § Partner Preferences · plain
May combine two claims.
Findingown dataIn mixed-sex triads, focal male rats directed significantly more nape attacks toward female partners than male partners, and a higher proportion of their play toward females than expected by chance.
“only males exhibited sex‐based preferences, directing significantly more playful attacks toward females than males.”
- Also stated in: § Partner Preferences · plain
“The number of nape attacks male rats directed toward male and female partners in mixed‐sex groups (Figure 2a) differed significantly (paired t‐test: t 7 = 5.444, p = 0.0010), with males attacking female partners more than males.”
- Also stated in: § Partner Preferences · plain
“Similarly, males directed a higher proportion of their play toward female partners than what would be expected by chance (one‐sample t‐test: t 7 = 4.769, p = 0.0020) (Figure 2b).”
Quote in the paperSubstantial claim- Also stated in: § Partner Preferences · plain
May combine two claims.
Findingown dataFemales playing in all-female groups initiated play at male-typical levels, just as many playful attacks as males playing in mixed-sex groups.
“females initiated play at male‐typical levels in all‐female triads”
- Also stated in: § Conclusion · plain
“When playing in all‐female groups, females initiated just as many playful attacks as males playing in mixed‐sex groups.”
Quote in the paperSubstantial claim- Also stated in: § Conclusion · plain
The quote only partly states this claim.
Findingown dataMales initiated more play than females.
“Like previous reports, we found that males initiated more play than females”
Quote in the paperSubstantial claimMay combine two claims.
Findingown dataMost females preferred to play with the opposite sex, but some preferred to play with other females.
“Most preferred to play with the opposite sex, but some preferred to play with other females.”
Quote in the paperSubstantial claimClassified as probably not a substantial claim.
Study design and conductreasoningTesting both frequency and proportion of attacks ensured that high players did not bias the statistical tests.
“By testing both the frequency and proportion, we ensured that the “high players” do not bias the statistical tests.”
Quote in the paperSubstantial claimMay combine two claims.
InterpretationcitationWhereas androgens may set a base frequency of play, other circulating hormones and neurotransmitters, such as endogenous opioids, can modulate how much rats play depending on social context.
“This suggests that whereas androgens may set a base frequency of play, other circulating hormones and neurotransmitters, such as endogenous opioids (Achterberg et al. 2019; Vanderschuren et al. 1995), can modulate how much rats play depending on the social context in which they find themselves (Achterberg et al. 2023).”
Quote in the paperSubstantial claim0 of 3 sources checkedClassified as probably not a substantial claim. May combine two claims.
Study design and conductreasoningFocal females were tested in both all-female and mixed-sex triads across separate sessions, allowing within-subject comparisons of play initiation as a function of group composition.
“Critically, focal females were tested in both all‐female and mixed‐sex triads across separate sessions, allowing within‐subject comparisons of play initiation as a function of group composition.”
Quote in the paperSubstantial claimProbably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.
PremisecitationRTP in rats mostly involves competing to access the partner's nape of the neck, which, if contacted, is gently nuzzled with the snout.
“RTP in rats mostly involves competing to access the partner's nape of the neck, which, if contacted, is gently nuzzled with the snout (Pellis and Pellis 1987; Siviy and Panksepp 1987).”
Quote in the paperNot a substantial claim0 of 2 sources checked- cites Pellis and Pellis 1987
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
- cites Siviy and Panksepp 1987 source
May combine two claims.
InterpretationreasoningThe males' preference to play with females is robust and not masked by a general motivation to play.
“Given that social isolation increases the motivation of rats to play (Panksepp and Beatty 1980; Pellis et al. 1997), this suggests that the males' preference to play with females is robust, not being masked by a general motivation to play.”
Quote in the paperSubstantial claim0 of 2 sources checkedMay combine two claims.
Interpretationown dataThe findings demonstrate two distinct forms of sex differences in rat play: partner choice and play frequency.
“These findings demonstrate two distinct forms of sex differences in the play of rats: partner choice and play frequency.”
Quote in the paperSubstantial claimClassified as probably not a substantial claim.
Study design and conductown dataParametric tests were used after confirming all data were normally distributed with a Shapiro-Wilk test (p > 0.05).
“Parametric tests were used after finding that all data were normally distributed with a Shapiro–Wilk test (p > 0.05).”
Quote in the paperSubstantial claimMay combine two claims.
Interpretationown dataMales preferentially engage with females, whereas females appear more flexible, forming idiosyncratic preferences independent of the partner's sex.
“Whereas males preferentially engage with females, females appear more flexible, forming idiosyncratic preferences independent of the partner's sex.”
Quote in the paperSubstantial claimProbably not a substantial claim: may not pass S3 (load-bearing).
Study design and conductreasoningSample sizes were based on group numbers used in prior studies rather than an a priori power analysis because variance estimates for triadic play measures are limited.
“Sample sizes were based on group numbers used in our prior studies employing similar social play paradigms (Ham et al. 2025; Ham and Pellis 2023, 2024, 2025), rather than on an a priori power analysis, as variance estimates for triadic play measures are currently limited.”
Quote in the paperNot a substantial claim0 of 3 sources checked- cites Ham et al. 2025
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
- cites Ham and Pellis 2023 source
- cites Ham and Pellis 2024
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
May combine two claims.
Study design and conductown dataOur analyses focused on play initiated by focal animals, and we did not quantify initiation by non-focal partners, so we cannot distinguish changes in motivation from changes in opportunity.
“Because our analyses focused on play initiated by focal animals, we did not quantify initiation by non‐focal partners and therefore cannot distinguish changes in motivation from changes in opportunity.”
Quote in the paperSubstantial claimMay combine two claims.
Study design and conductown dataThe sample size of this study was small; if we had a larger sample size, the preference for opposite sex by females likely would have been significant.
“One important caveat is the sample size of this study. Given that 6/8 females preferred the opposite sex, if we had a larger sample size, this likely would have been significant.”
Quote in the paperNot a substantial claimMay combine two claims.
InterpretationreasoningThe influence of mixed-sex groups has both a chronic and an acute effect on female play.
“suggesting that the influence of mixed‐sex groups has both a chronic and an acute effect on female play.”
Quote in the paperSubstantial claimProbably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.
PremisecitationSub-adult female rats spend more time interacting with strains of greater genetic similarity, whereas males prefer strains that are more novel.
“Additionally, sub‐adult female rats spend more time interacting with strains of greater genetic similarity, whereas males prefer strains that are more novel (Ippongi et al. 2025).”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites Ippongi et al. 2025 source
May combine two claims.
Interpretationown dataSex differences in play initiation are context dependent and emerge from social dynamics rather than fixed individual differences.
“indicating that sex differences in play initiation are context dependent and emerge from social dynamics rather than fixed individual differences.”
Quote in the paperSubstantial claim
The paper relies on this without support.
The 2.5 h social isolation period increases play motivation without altering partner preferences.
“Following the 2 days of habituation, the animals were weighed and then socially isolated for 2.5 h, with food and water provided ad libitum. All rats, including focal rats, were isolated for 2.5 h.”
The paper relies on this without support.
Repeated testing of the same rats across different group compositions and roles does not substantially affect their play behavior or partner preferences.
“Because of the limited cohort size (16 females, 10 males), animals participated in more than one test session across different group compositions. Rats could serve as focal animals in some sessions and as non‐focal partners in others, with test sessions separated in time.”
Self-check
Percentages, sums and reported differences re-computed from the paper’s own numbers.
Each contradiction between two passages listed here was confirmed by an independent check.
Figure 3 caption denies a reported difference in female play
MajorThe Figure 3 caption says female play did not differ between same-sex and mixed-sex groups, but the Results report that females played significantly less in mixed-sex groups (p = 0.031). This is a conclusion-bearing comparison.
“This difference, however, is not present when the total play males engaged in is compared to the total play the females engaged when playing in same‐sex groups or when the total play the focal females engaged in when playing in same‐sex groups is compared to when they played in mixed‐sex groups.”
“Post hoc comparisons revealed that the females in mixed‐sex groups played significantly less than when they were in all‐female groups (p = 0.031), whereas males played more than females in such groups (p = 0.016).”
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What is play fighting and what is it good for?
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“Indeed, individuals engaging in RTP cooperate to some degree so that both have the opportunity to attack and defend themselves (Ham, Pellis, and Pellis 2024; Palagi et al. 2016; Palagi 2023; Pellis and Pellis 2017).”
Self-citationSex differences in the play behavior of prepubescent rats
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Effects of morphine on different aspects of social play in juvenile rats
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“…androgens may set a base frequency of play, other circulating hormones and neurotransmitters, such as endogenous opioids (Achterberg et al. 2019; Vanderschuren et al. 1995), can modulate how much rats play depending on the social context in which they find themselves (Achterberg et al. 2023).”
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Self-citationPlay-solicitation behavior in juvenile male and female rats
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“…the sex effect (Achterberg et al. 2024; Argue and McCarthy 2015; Northcutt and Nwankwo 2018; Orsucci et al. 2025; Parent and Meaney 2008; Pellis et al. 1997; Siviy 2018; Siviy et al. 1990, 2003, 2017; Siviy et al. 2017; Siviy and Panksepp 1987; Thor and Holloway 1983, 1984; Veenema et al. 2013).”
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“…the sex effect (Achterberg et al. 2024; Argue and McCarthy 2015; Northcutt and Nwankwo 2018; Orsucci et al. 2025; Parent and Meaney 2008; Pellis et al. 1997; Siviy 2018; Siviy et al. 1990, 2003, 2017; Siviy et al. 2017; Siviy and Panksepp 1987; Thor and Holloway 1983, 1984; Veenema et al. 2013).”
Fair play and its connection with social tolerance, reciprocity and the ethology of peace
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“Indeed, individuals engaging in RTP cooperate to some degree so that both have the opportunity to attack and defend themselves (Ham, Pellis, and Pellis 2024; Palagi et al. 2016; Palagi 2023; Pellis and Pellis 2017).”
Characterization of juvenile play in rats: importance of sex of self and sex of partner
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Self-citationSocial play among juvenile wild Japanese macaques (Macaca fuscata) strengthens their social bonds
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Self-citationThe neurobiology of social play behaviour: Past, present and future
Achterberg, E. J. M., & Vanderschuren, L. J. M. J. (2023) · Neuroscience & Biobehavioral Reviews · doi:10.1016/j.neubiorev.2023.105319 · Cited by 56 · cited 1× · see citing works
“Rats less motivated to play are more inclined to evade an attack than roll over to supine (Pellis et al. 1997; Varlinskaya et al. 1999) as rolling to supine is thought to be an active solicitation of the partner, so facilitating the continuation of play (Achterberg and Vanderschuren 2023).”
Opioid modulation of social play reward in juvenile rats
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“This suggests that whereas androgens may set a base frequency of play, other circulating hormones and neurotransmitters, such as endogenous opioids (Achterberg et al. 2019; Vanderschuren et al. 1995), can modulate how much rats play depending on the social context in which they find themselves…”
Sexually dimorphic role for vasopressin in the development of social play
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“Though sex differences are not always reported (Aguilar 2010; Field et al. 2006; S. M. Himmler et al. 2014; Madden and Zup 2014; Paul et al. 2014), we found that males launched more nape attacks than females when playing in mixed-sex groups (Casto et al. 2003; Meaney and McEwen 1986; Pellis and…”
Adult play and the evolution of tolerant and cooperative societies
Palagi, E. (2023) · Neuroscience & Biobehavioral Reviews · doi:10.1016/j.neubiorev.2023.105124 · Cited by 45 · cited 1× · see citing works
“Indeed, individuals engaging in RTP cooperate to some degree so that both have the opportunity to attack and defend themselves (Ham, Pellis, and Pellis 2024; Palagi et al. 2016; Palagi 2023; Pellis and Pellis 2017).”
Anosmia and play fighting behavior in prepubescent male and female rats
Thor, D. H., & HOLLOWAYJR, W. (1982) · Physiology & Behavior · doi:10.1016/0031-9384(82)90016-6 · Cited by 45 · cited 1× · see citing works
“…et al. 2006; S. M. Himmler et al. 2014; Madden and Zup 2014; Paul et al. 2014), we found that males launched more nape attacks than females when playing in mixed-sex groups (Casto et al. 2003; Meaney and McEwen 1986; Pellis and Pellis 1990; Stockman and McCarthy 2017; Thor and Holloway 1982, 1984).”
The development of socio-sexual behavior in belugas (Delphinapterus leucas) under human care
Lilley, M. K., Ham, J. R., & Hill, H. M. M. (2019) · Behavioural Processes · doi:10.1016/j.beproc.2019.104025 · Cited by 34 · cited 2× · see citing works
“However, these preferences for same-sex play partners can change with age (Ham et al. 2022; Lilley et al. 2020) or depending on the type of RTP performed (Manitzas Hill, Ortiz, et al. 2022).”
Self-citationDevelopmental origins of sex differences in the neural circuitry of play
VanRyzin, J. W., Marquardt, A. E., & McCarthy, M. M. (2020) · International Journal of Play · doi:10.1080/21594937.2020.1723370 · Cited by 34 · cited 2× · see citing works
“It is these underlying androgens during the neonatal period that seem to be responsible for the sex differences in levels of play initiation and do so by affecting the neural circuitry associated with play behavior (VanRyzin et al. 2020b).”
Measuring play fighting in rats: a multilayered approach
Pellis, S. M., Pellis, V. C., Burke, C. J., Stark, R. A., Ham, J. R., Euston, D. R., & Achterberg, E. J. M. (2022) · Current Protocols · doi:10.1002/cpz1.337 · Cited by 33 · cited 4× · see citing works
“Playful attacks were scored when the snout of one rat was in contact with, or was directed toward, the nape of another rat (Pellis, Pellis, Burke, et al. 2022).”
InfluentialSelf-citationMarquardt, A. E., VanRyzin, J. W., Fuquen, R. W., & McCarthy, M. M. (2023) · Frontiers in Behavioral Neuroscience · doi:10.3389/fnbeh.2022.1076765 · Cited by 31 · cited 1× · see citing works
“…Pellis, Ham, and Achterberg 2022), it has been used extensively to study the mechanisms regulating social behavior and the development of associated brain systems (e.g., Bagi et al. 2022; Ham, Szabo, et al. 2024; Marquardt et al. 2023; Reinhold et al. 2019; Stark et al. 2023; Veenema et al. 2013).”
Field, E. F., Whishaw, I. Q., Pellis, S. M., & Watson, N. V. (2006) · Developmental Psychobiology · doi:10.1002/dev.20121 · Cited by 30 · cited 1× · see citing works
“Though sex differences are not always reported (Aguilar 2010; Field et al. 2006; S. M. Himmler et al. 2014; Madden and Zup 2014; Paul et al. 2014), we found that males launched more nape attacks than females when playing in mixed-sex groups (Casto et al. 2003; Meaney and McEwen 1986; Pellis and…”
Self-citationThe rough-and-tumble play of rats as a natural behavior suitable for studying the social brain
Pellis, S. M., Pellis, V. C., Ham, J. R., & Achterberg, E. J. M. (2022) · Frontiers in Behavioral Neuroscience · doi:10.3389/fnbeh.2022.1033999 · Cited by 29 · see citing works
Self-citationUnsupervised discovery of behaviorally relevant brain states in rats playing hide-and-seek
Bagi, B., Brecht, M., & Sanguinetti-Scheck, J. I. (2022) · Current Biology · doi:10.1016/j.cub.2022.04.068 · Cited by 27 · cited 1× · see citing works
“…Pellis, Ham, and Achterberg 2022), it has been used extensively to study the mechanisms regulating social behavior and the development of associated brain systems (e.g., Bagi et al. 2022; Ham, Szabo, et al. 2024; Marquardt et al. 2023; Reinhold et al. 2019; Stark et al. 2023; Veenema et al. 2013).”
Madden, A. M. K., & Zup, S. L. (2014) · Physiology & Behavior · doi:10.1016/j.physbeh.2014.01.036 · Cited by 26 · cited 1× · see citing works
“Though sex differences are not always reported (Aguilar 2010; Field et al. 2006; S. M. Himmler et al. 2014; Madden and Zup 2014; Paul et al. 2014), we found that males launched more nape attacks than females when playing in mixed-sex groups (Casto et al. 2003; Meaney and McEwen 1986; Pellis and…”
Stark, R. A., Brinkman, B., Gibb, R. L., Iwaniuk, A. N., & Pellis, S. M. (2022) · Behavioural Brain Research · doi:10.1016/j.bbr.2022.114222 · Cited by 23 · cited 1× · see citing works
“…Pellis, Ham, and Achterberg 2022), it has been used extensively to study the mechanisms regulating social behavior and the development of associated brain systems (e.g., Bagi et al. 2022; Ham, Szabo, et al. 2024; Marquardt et al. 2023; Reinhold et al. 2019; Stark et al. 2023; Veenema et al. 2013).”
Self-citationLesscher, H. M. B., Achterberg, E. J. M., Siviy, S. M., & Vanderschuren, L. J. M. J. (2021) · Psychopharmacology · doi:10.1007/s00213-021-05929-1 · Cited by 23 · cited 1× · see citing works
“Rats show considerable individual variation in RTP, with some individuals being more playful than others (Achterberg et al. 2023; Ham and Pellis 2023; Lampe et al. 2019; Lesscher et al. 2021; Pellis and McKenna 1992).”
Ham, J. R., Lilley, M. K., Lelekach, J., Miller, M. R., Robeck, T. R., Pellis, S. M., & Hill, H. M. M. (2022) · Behavioural Processes · doi:10.1016/j.beproc.2022.104695 · Cited by 22 · cited 1× · see citing works
“However, these preferences for same-sex play partners can change with age (Ham et al. 2022; Lilley et al. 2020) or depending on the type of RTP performed (Manitzas Hill, Ortiz, et al. 2022).”
Self-citationHam, J., & Pellis, S. (2023) · Animal Behavior and Cognition · doi:10.26451/abc.10.04.02.2023 · Cited by 22 · cited 6× · see citing works
“When tested in groups, where the individuals are of varying fa-miliarity (i.e., cage mate, individual on the other side of a clear and perforated divider, or a complete stranger), males prefer to play with novel, unfamiliar partners over familiar cage mates (Ham and Pellis 2023).”
InfluentialSelf-citationSex differences in juvenile play behavior differ among rat strains
Northcutt, K. V., & Nwankwo, V. C. (2018) · Developmental Psychobiology · doi:10.1002/dev.21760 · Cited by 20 · cited 1× · see citing works
“…in female play, and not a change in the frequency of male play, that drives the sex effect (Achterberg et al. 2024; Argue and McCarthy 2015; Northcutt and Nwankwo 2018; Orsucci et al. 2025; Parent and Meaney 2008; Pellis et al. 1997; Siviy 2018; Siviy et al. 1990, 2003, 2017; Siviy et al.…”
Play like me: Similarity in playfulness promotes social play
Lampe, J. F., Ruchti, S., Burman, O., Würbel, H., & Melotti, L. (2019) · PLOS ONE · doi:10.1371/journal.pone.0224282 · Cited by 20 · cited 1× · see citing works
“Rats show considerable individual variation in RTP, with some individuals being more playful than others (Achterberg et al. 2023; Ham and Pellis 2023; Lampe et al. 2019; Lesscher et al. 2021; Pellis and McKenna 1992).”
Achterberg, E. J. M., Burke, C. J., & Pellis, S. M. (2023) · Behavioural Processes · doi:10.1016/j.beproc.2023.104933 · Cited by 20 · cited 5× · see citing works
“…androgens may set a base frequency of play, other circulating hormones and neurotransmitters, such as endogenous opioids (Achterberg et al. 2019; Vanderschuren et al. 1995), can modulate how much rats play depending on the social context in which they find themselves (Achterberg et al. 2023).”
InfluentialSelf-citationStark, R. A. M., Ramkumar, R., & Pellis, S. M. (2021) · International Journal of Comparative Psychology · doi:10.46867/ijcp.2021.34.5592 · Cited by 20 · see citing works
Self-citationIdazoxan increases rough-and-tumble play, activity and exploration in juvenile rats
Siviy, S. M., Atrens, D. M., & Menendez, J. A. (1990) · Psychopharmacology · doi:10.1007/bf02245801 · Cited by 19 · see citing works
Ham, J. R., Szabo, M., Annor‐Bediako, J., Stark, R. A., Iwaniuk, A. N., & Pellis, S. M. (2024) · Developmental Psychobiology · doi:10.1002/dev.22456 · Cited by 18 · cited 2× · see citing works
“Indeed, individuals engaging in RTP cooperate to some degree so that both have the opportunity to attack and defend themselves (Ham, Pellis, and Pellis 2024; Palagi et al. 2016; Palagi 2023; Pellis and Pellis 2017).”
Self-citationEffects of cross-fostering on play and anxiety in juvenile Fischer 344 and Lewis rats
Siviy, S. M., Eck, S. R., McDowell, L. S., & Soroka, J. A. (2016) · Physiology & Behavior · doi:10.1016/j.physbeh.2016.11.035 · Cited by 17 · cited 1× · see citing works
“…the sex effect (Achterberg et al. 2024; Argue and McCarthy 2015; Northcutt and Nwankwo 2018; Orsucci et al. 2025; Parent and Meaney 2008; Pellis et al. 1997; Siviy 2018; Siviy et al. 1990, 2003, 2017; Siviy et al. 2017; Siviy and Panksepp 1987; Thor and Holloway 1983, 1984; Veenema et al. 2013).”
Predator odor exposure of rat pups has opposite effects on play by juvenile males and females
Stockman, S. L., & McCarthy, M. M. (2016) · Pharmacology Biochemistry and Behavior · doi:10.1016/j.pbb.2016.08.008 · Cited by 16 · cited 1× · see citing works
“…et al. 2006; S. M. Himmler et al. 2014; Madden and Zup 2014; Paul et al. 2014), we found that males launched more nape attacks than females when playing in mixed-sex groups (Casto et al. 2003; Meaney and McEwen 1986; Pellis and Pellis 1990; Stockman and McCarthy 2017; Thor and Holloway 1982, 1984).”
Assessing Rough-and-tumble Play Behavior in Juvenile Rats
VanRyzin, J., Marquardt, A., & McCarthy, M. (2020) · BIO-PROTOCOL · doi:10.21769/bioprotoc.3481 · Cited by 16 · see citing works
Pellis, S. M., Pellis, V. C., & Ham, J. R. (2024) · Frontiers in Ethology · doi:10.3389/fetho.2024.1362052 · Cited by 15 · cited 2× · see citing works
“One of the most common forms of social play is play fighting, or rough- and-tumble play (RTP), in which partners compete with one another to gain an advantage over one another, such as nuz-zling, grooming, or biting a particular body target (Aldis 1975; Pellis et al. 2024).”
Self-citationInfantile experience and play motivation
Aguilar, R. (2010) · Social Neuroscience · doi:10.1080/17470919.2010.503618 · Cited by 14 · cited 1× · see citing works
“Though sex differences are not always reported (Aguilar 2010; Field et al. 2006; S. M. Himmler et al. 2014; Madden and Zup 2014; Paul et al. 2014), we found that males launched more nape attacks than females when playing in mixed-sex groups (Casto et al. 2003; Meaney and McEwen 1986; Pellis and…”
Treatment with low doses of nicotine but not alcohol affects social play reward in rats
Achterberg, E. J. M., & Vanderschuren, L. J. M. J. (2020) · International Journal of Play · doi:10.1080/21594937.2020.1720121 · Cited by 13 · cited 1× · see citing works
“…of ways (Pellis, Pellis, Burke, et al. 2022), rotating along the horizontal access of the body, so that the attacked rat is in a supine position, is one of the most common responses and most frequently measured (e.g., Achterberg and Vanderschuren 2020; Siviy et al. 2023; Veenema et al. 2013).”
Playful mouth‐to‐mouth interactions of belugas (Delphinapterus leucas) in managed care
Ham, J. R., Lilley, M. K., Wincheski, R. J., Miranda, J., Velarde, A. G., Kolodziej, K., Pellis, S. M., & Hill, H. M. M. (2023) · Zoo Biology · doi:10.1002/zoo.21788 · Cited by 13 · cited 3× · see citing works
“Whereas the target varies depending on the species, the targets competed over are often the same as those in serious fighting or those that are contacted during greeting, sex, or predation (Ham et al. 2023; Manitzas Hill, Ham, and Lilley 2022; Pellis 1988; Pellis et al. 2023).”
Self-citationPlay partner preferences among groups of unfamiliar juvenile male rats
Ham, J. R., & Pellis, S. M. (2024) · Scientific Reports · doi:10.1038/s41598-024-66988-w · Cited by 13 · see citing works
Self-citationSocial games that belugas (Delphinapterus leucas) play
Hill, H. M. M., Ortiz, N., Kolodziej, K., & Ham, J. R. (2022) · International Journal of Play · doi:10.1080/21594937.2022.2152536 · Cited by 12 · see citing works
Self-citationPredatory aggression in the mink (Mustela vison): Roles of serotonin and food satiation
Nikulina, E. M., & Popova, N. K. (1988) · Aggressive Behavior · doi:10.1002/1098-2337(1988)14:2 · Cited by 12 · see citing works
Observations of Mating Practice by Non-Sexually Mature Male Belugas (Delphinapterus leucas)
Hill, H. M. M., Ham, J. R., & Lilley, M. K. (2022) · Aquatic Mammals · doi:10.1578/am.48.6.2022.541 · Cited by 10 · see citing works
Self-citationNeurexin1α knockout in rats causes aberrant social behaviour: relevance for autism and schizophrenia
Achterberg, E. J. M., Biemans, B., & Vanderschuren, L. J. M. J. (2025) · Psychopharmacology · doi:10.1007/s00213-024-06559-z · Cited by 9 · see citing works
Effects of neonatal handling on play and anxiety in F344 and Lewis rats
Siviy, S. M. (2018) · Developmental Psychobiology · doi:10.1002/dev.21622 · Cited by 6 · cited 1× · see citing works
“…the sex effect (Achterberg et al. 2024; Argue and McCarthy 2015; Northcutt and Nwankwo 2018; Orsucci et al. 2025; Parent and Meaney 2008; Pellis et al. 1997; Siviy 2018; Siviy et al. 1990, 2003, 2017; Siviy et al. 2017; Siviy and Panksepp 1987; Thor and Holloway 1983, 1984; Veenema et al. 2013).”
The evolution of aggressive and amicable play fighting in primates: a phylogenetic perspective
Pellis, S. M., Pellis, V. C., & Ham, J. R. (2022) · International Journal of Play · doi:10.1080/21594937.2022.2152537 · Cited by 6 · see citing works
Self-citationOppositions, joints, and targets: the attractors that are the glue of social interactions
Ham, J. R., Pellis, S. M., & Pellis, V. C. (2024) · Frontiers in Behavioral Neuroscience · doi:10.3389/fnbeh.2024.1451283 · Cited by 5 · cited 1× · see citing works
“Indeed, individuals engaging in RTP cooperate to some degree so that both have the opportunity to attack and defend themselves (Ham, Pellis, and Pellis 2024; Palagi et al. 2016; Palagi 2023; Pellis and Pellis 2017).”
Self-citationHam, J. R., & Pellis, S. M. (2025) · iScience · doi:10.1016/j.isci.2025.112562 · Cited by 5 · cited 3× · see citing works
“Given this variation, some rats might serve as more compatible play partners than others (Ham et al. 2025; Ham and Pellis 2023, 2024, 2025).”
Self-citationJuvenile male rats form preferences based on strain when playing in groups but not in pairs
Ham, J. R., Jaiswal, D., Waner-Mariquito, R., Pellis, S. M., & Achterberg, E. J. M. (2025) · Frontiers in Behavioral Neuroscience · doi:10.3389/fnbeh.2025.1617178 · Cited by 5 · see citing works
Self-citationOrsucci, I. C., Becker, K. D., Ham, J. R., Lee, J. D. A., Bowden, S. M., & Veenema, A. H. (2025) · Physiology & Behavior · doi:10.1016/j.physbeh.2025.115080 · Cited by 3 · cited 4× · see citing works
“…not a change in the frequency of male play, that drives the sex effect (Achterberg et al. 2024; Argue and McCarthy 2015; Northcutt and Nwankwo 2018; Orsucci et al. 2025; Parent and Meaney 2008; Pellis et al. 1997; Siviy 2018; Siviy et al. 1990, 2003, 2017; Siviy et al. 2017; Siviy and Panksepp…”
InfluentialSelf-citationIppongi, Y., Kiyokawa, Y., & Takeuchi, Y. (2025) · Behavioural Processes · doi:10.1016/j.beproc.2025.105298 · Cited by 3 · cited 1× · see citing works
“Additionally, sub-adult female rats spend more time interacting with strains of greater genetic similarity, whereas males prefer strains that are more novel (Ippongi et al. 2025).”
Noradrenergic modulation of play in Sprague-Dawley and F344 rats
Siviy, S. M., Martin, M. A., & Campbell, C. M. (2023) · Psychopharmacology · doi:10.1007/s00213-023-06419-2 · Cited by 3 · see citing works
Bekoff, M., & Fagen, R. (1981) · Evolution · doi:10.2307/2408140 · Cited by 2
Aldis, O. (1975) · Play Fighting · doi:10.1016/b978-0-12-049450-7.50014-2
Flagged first, then by citations
Research works printed but not linked: 2
- Fry D. P., 2005, The Nature of Play: Great Apes and Humans
- Pellis S. M., 2009, The Playful Brain: Venturing to the Limits of Neuroscience
Cited by
Sorted by citations
Evaluating the play fighting of rats: A sociological perspective
Ham, J. R., Pellis, S. M., Pellis, V. C., & Achterberg, E. J. M. (2026) · Journal of Neuroscience Methods · doi:10.1016/j.jneumeth.2026.110836
Self-citation
- Authors
- Ham, J. R., Pellis, S. M., & McDonald, R. J.
- Affiliations
- University of Lethbridge (CA)
- Corresponding author
- Ham, Jackson R.
- Venue
- European Journal of Neuroscience
- Publisher
- Wiley
- Published
- 2026-02
- Volume
- 63
- Issue
- 3
- Pages
- e70426-e70426
- ISSN
- 0953-816X (ISSN-L)
- 1460-9568
- PMC
- PMC12892013
- OpenAlex
- W7128482395
- Semantic Scholar
- dca7ca6b36434c7d27e3a920f29252d70840cae4
- Cited by
- 1
- References
- 55
- Citations by year
- 2026: 1
- FWCI
- 8.83
- Type
- journal article
- Language
- en
- Open access
- hybrid
- doi.org
- Licence
- Locations
- European Journal of Neuroscience (publishedVersion, cc-by)
- PubMed (publishedVersion)
- Europe PMC (PubMed Central) (submittedVersion, cc-by)
- PubMed Central (submittedVersion, cc-by)
- Funders
- University of Lethbridge
- Natural Sciences and Engineering Research Council of Canada (RGPIN‐2020‐06929)
- Topics
- Social Sciences › Psychology › Social Psychology › Neuroendocrine regulation and behavior
- Life Sciences › Agricultural and Biological Sciences › Ecology, Evolution, Behavior and Systematics › Animal Behavior and Reproduction
- Social Sciences › Psychology › Social Psychology › Primate Behavior and Ecology
- Keywords
- rough-and-tumble play, partner choice, sex differences, young rats, play frequency, social environment, social decision-making, defensive behavior
- MeSH terms
- Animals, Behavior, Animal, Choice Behavior, Female, Male, Play and Playthings, Sex Characteristics, Social Behavior, Rats, Wistar, Rats
About these checks
Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.
Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-12.
Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-12.
Cited sources are checked by gpt-6-sol.
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