The processing-speed theory of adult age differences in cognition

“Although common factors such as generalized slowing have been proposed to explain the disrupting effects of task complexity with age (Salthouse, 1996), significant age effects remain after adequately controlling for differences in processing speed”

“For example, Parkin and Java (1999) found reliable age differences on all frontal measures except for verbal fluency, a finding consistent with several previous studies showing word fluency to be relatively age insensitive (Parkin, Walter, & Hunkin, 1995; Salthouse, 1993, 1996a, 1996b).”

“This presents a puzzle: Slowing for older adults has often been interpreted as a deficit such that, for example, cognitive operations are not fully completed in the available time or the products of earlier operations are not fully available for later operations (e.g., Salthouse, 1996).”

“Taken together, the results indicate that even for speed-based indicators of neurocognitive integrity (e.g., Dixon et al., 2007; Salthouse, 1996), significant change did not occur until well into the late-life years.”

“This type of review considers knowledge about a specific topic and seeks to identify, analyse and synthesise results of independent studies on the same subject [36,37].”

“…the first explanation, a word generation deficit would be induced by the decline in executive functions (Craik and Byrd 1982) and/or processing speed (Salthouse 1996) as a result of aging-related anatomical reductions within the frontal lobes (Raz et al. 2007; Ullman and Pierpont 2005; West 2000).”

“Why would psychomotor speed, as measured by DSST, be a predictor? Digit Symbol Substitution is a classic indicator of psychomotor speed used by Salthouse [10] and many others to explore issues related to cognition and ageing [31, 32].”

“The fact that slowing down and complexity loss in dFC are associated with degraded general performance can be linked to prominent theories of cognitive aging, speculatively establishing alterations of dFC random walk properties as novel imaging correlates of processing speed reduction (Salthouse, 1996; Finkel et al.,…”

“However, there is good evidence that cognitive declines begin early in life (Salthouse, 1996; Singh-Manoux et al., 2011); between-person differences in cognitive decline rates would also contribute to cognitive performance gradients seen in this study.”

“Although some cognitive functions, including world knowledge, verbal abilities [8,9,10] and implicit memory [11,12,13,14,15,16,17] are preserved in older adults, normal aging is associated with a significant decline in certain cognitive functions such as attention, episodic memory, working memory, processing speed, an…”

“Behavioral studies implicate an age-related slowing in general information processing speed as a partial cause of related declines in cognitive functions such as memory (Salthouse, 1996) and general fluid intelligence (Eysenck, 1982; Jensen, 1993).”

“In general, all subcomponents of control follow a common pattern of maturation during childhood and adolescence and of decline in older age that parallels the development of frontal lobe functions (Hasher & Zacks 1988; Wingfield et al. 1988; Salthouse 1996; Stuss 2011).”

“…in our meta-analysis confirms a robust trend present in literature: an increase in RTs and/or RT variability with age in different cognitive tasks (e.g., Der & Deary, 2006; Dykiert et al., 2012; Salthouse, 1996), including attentional tasks (e.g., Fortenbaugh et al., 2015; Lufi & Haimov, 2019).”

“Relevant cognitive models include abnormal internal, temporal information processing dynamics, or bcognitive dysmetria,Q undermining the coordination of various concurrent and successive processing operations (Andreasen et al., 1998; Salthouse, 1996).”

“51,57 If decreased processing speed is responsible for impaired working memory, skill acquisition, and overall cognitive performance in older adults as is re-inforced by other research, 49–51 , 14 PENGELLY ET AL.”

“Additionally, previous research has suggested that aging is associated with a general decline in the amount and rate of processing (Craik & Byrd, 1982; Salthouse, 1999).”

“Processing speed has been proposed to account for other age-related differences in cognitive ability (Salthouse, 1996).”

“Processing speed has been thought to be one of the main cognitive factors affected in normal aging (Salthouse, 1996).”

“Speed of processing declines during aging (Salthouse, 1996).”

“Some neurocognitive models have already been proposed for older individuals, such as the vulnerability of anterior brain systems in aging [141, 142]; the brain reorganization hypothesis proposed in the HAROLD model; and the posterior anterior shift in aging [80, 143].”

“Perhaps, age represents cognitive decline different from working memory capacity, such as processing speed (Salthouse, 1996) or attention (Craik & Byrd, 1982), both of which might affect performance in demanding speech-in-noise situations (e.”

“This is consistent with developmental work showing increases in processing speed in children and adolescents [Kail, 1991] and declines in adulthood and later life [Salthouse, 1996].”

“which an individual performs a cognitive activity, is one of the best indicators of cognitive aging (Salthouse, 1996).”

“In line with the hypothesis of a general slowdown with age, contributing to a decline in accuracy in many different cognitive functions (Salthouse, 1996), processing speed also seems to mediate age-related PM decline (Salthouse, Berish, & Siedlecki, 2004).”

“…step of a computation process, which predicts more pronounced deficits for more complex abilities (Cerella, 1990; Maylor & Valentine, 1992; Salthouse, 1996a, 1996b), deficits at each stage of the face recognition process (Maylor, 1990), and an increased need for cognitive resources during…”

“Studies of the normal population suggest that cognitive decline in fluid intelligence in older people is related to cognitive slowing (e.g. Salthouse, 1996) and, when decision speed is taken into account in the analyses, most of the variance in other measures of memory and executive function are…”

“…learning: (a) cognitive slowing may hinder elderly adults from having multiple representations simultaneously activated (see simultaneity theory of Salthouse, 1996); (b) associative binding deficits may cause impairment in making associations between multiple stimuli or stimulus features and…”

“…to higher cognitive functions such as executive control and fluid intelligence (Gf; Baltes & Lindenberger, 1997; Bugg, Zook, DeLosh, Davalos, & Davis, 2006; Park et al., 2002; Ryan, Sattler, & Lopez, 2000; Salthouse, 1996), and, ultimately, everyday life functioning (Alzheimer’s Association, 2011).”

“Inhibition–reduction theory (Hasher & Zacks, 1988) is one of several theories proposed to account for the age-related decline in WM span (Light, 1991; Salthouse, 1996; see Zacks, Hasher, & Li, 2000).”

“Salthouse (1992, 1996) argues that age-related declines in complex task performance parallel reductions in working memory and information processing speed (Salthouse & Babcock, 1991).”

“Furthermore, we found a consistent difference in reaction time between the young adults and elderly, which is in line with the notion that many aspects of information processing become less efficient with increasing age [33].”

“Evidence for the decline in processing speed and its effect on cognitive functions in aging is ubiquitous (11).”

“Older adults perform poorer than young on the speed of processing measure, which is a robust finding for cognitive aging studies (Salthouse, 1996).”

“Also, there is evidence pointing towards an age related decrease in openness (Roberts, Walton, & Viechtbauer, 2006) and an age related increase in NFC (e.g. Hess, 2001; Salthouse, 1996).”

“Such improvements in brain activation and/or structure delay the onset and/or may reduce the risk of cognitive slowing, which is the most significant contributor to overall cognitive decline (Salthouse, 1996; 2009).”

“This is also evident for subtests such as Trail Making A and Digit Symbol Coding that include a speeded component, which is known to be highly susceptible to age (Salthouse, 1996).”

“…within the field given the large body of evidence suggesting that processing speed has a major role in mediating relations between age and cognition.28 Processing Speed is among the most age-sensitive of the cognitive domains, as it is affected early in the aging process, and has therefore been…”

“These results raise questions about the potential impact of processing speed on other cognitive abilities within the population of older adult musicians (e.g., Salthouse, 1996).”

“Changes in hearing sensitivity [24], memory [25], attention [18], and speed of processing [28] have all been proposed to account for the difficulties older adults have in processing everyday speech.”

“Dunlosky and Salthouse (1996) also reported that multitrial free recall was less efficient for older adults than for younger adults, and interpreted their findings in terms of weaker representations of the to-be-remembered items.”

“many age-related cognitive deficits (Salthouse, 1996).”

“For example, older adults experience reduced information processing speed (e.g., Salthouse, 1992, 1996; Salthouse & Meinz, 1995); reduced working memory capacity (e.g., Bopp & Verhaeghen, 2005; Kemtes & Kemper, 1997; Salthouse & Meinz, 1995); reduced inhibitory control (e.g., Burke, 1997; Darowski,…”

“…1992; Kail & Salthouse, 1994; Miyake, Carpenter, & Just, 1994, 1995), and that processing speed is a major factor in agerelated cognitive decline (Salthouse, 1996), this has been overlooked in a number of WM studies with adults with aphasia (e.g., Christensen & Wright, 2010; Tompkins, Bloise,…”

“The aging burdens include cognitive decline, such as executive dysfunction (Jurado and Rosselli, 2007), memory deficits (Nilsson, 2003) and processing slowness (Salthouse, 1996), and brain mass decrease and ventricular expansion (Fjell and Walhovd, 2010).”

“For instance, cognitive aging is typically associated with reductions of attention and memory capacities (Salthouse, 1996; Chao and Knight, 1997; Maylor, 1998; Maylor and Lavie, 1998; Johnson et al., 2002; Hedden and Gabrieli, 2004; Anguera et al., 2011).”

“However, ageing is also associated with significant declines in processing speed, irrespective of executive deficits (Salthouse, 1996 ), and advanced age is linked to significant declines in categorical fluency (Winocur, Moscovitch, & Stuss, 1996 ), which might be related to categorical clustering.”

“Psychometric speed measures account for the larger part of cognitive declines in old age (Salthouse, 1996).”

“Age-related changes in selective attention have been reported (Zanto and Gazzaley, 2014), just as for other cognitive skills (e.g., Salthouse, 1996; Sander et al., 2012).”

“Taken together these data support the processing speed theory of cognitive ageing which postulates that processing speed is integral to the performance of fluid abilities and that the constraints of processing become more evident with age (Salthouse 1996).”

“This outcome may seem surprising given the demanding nature of span tasks and strategy deployment, but we recently became aware of an independent study that also demonstrated age equivalence in strategy production on the OSPAN task (Touron et al., 2007). Although Touron et al.’s (2007) focus was on meta-cognitive moni…”

“The findings from this study provide support for the general slowing account of cognitive aging (Salthouse, 1996) that provides a bridge between psychological theorizing about aging and cognition and the biological underpinnings .”

“…issue (Armbrüster et al., 2007; Birren and Fisher, 1995; Fisk and Rogers, 1997; Gilbert et al., 2004; Haegerstrom-Portnoy et al., 1999; Kline and Scialfa, 1997; Oetjen and Ziefle, 2007; Pak et al., 2008; Park, 1999; Salthouse, 1996; Westermann, 1997; Ziefle and Bay, 2006; Ziefle et al., 2007).”

“Some of these researchers have focused on the relation between age differences in speed and age differences in working memory (e.g., Dempster, 1981; Salthouse, 1996), whereas others have focused on the relation between individual differences in speed and individual differences in working memory…”

“Older adults’ lower processing capacity would make activating all of these items simultaneously more di Y cult (Salthouse 1996).”

“(6) Turning to speed of processing, studies generally agreed that processing speed declines with age(7,8) and that it is associated with progressive age-related structural brain changes,(9) which makes it an inevitable consequence of the aging process.”

“The tasks that make up Ga and Gsm appeared to elicit the most frustration in our older subjects, according to anecdotal reports from the research assistants.”

“More efficient processing would leave more resources available for handling incoming subsequent input (Salthouse, 1996), thus generally preventing overload in phonological short-term memory, which is proposed as being critical to phonological learning (Miyake & Friedman, 1998).”

“…and memory to later cognition, based on theoretical considerations (Gathercole & Pickering, 2000; Heitz, Unsworth, & Engle, 2005; Jensen, 1992; Salthouse, 1996) and our own findings that, when assessed at 11 years, these two aspects of cognition accounted for much of the preterm/full-term…”

“Salthouse, T. A. (1996). The processing-speed theory of adult age differences in cognition.”

“Systematic RT correlations between younger and older adults have led to the proposal of a global processing speed factor that governs adult-aging performance changes (e.g., Salthouse, 1996b; Cerella, 1991; Hale, Myerson, & Wagstaff, 1987).”

“…have systematically assessed perceptual and psychomotor speed in the same population and found that they share a common variance, arguing in favor of the presence of a general slowing of perceptuomotor, attentional, and cognitive processes (Cerella, 1985; Craik et al., 1990; Salthouse, 1996).”