The processing-speed theory of adult age differences in cognition

“This observation has some bearing on the neural bases for the pervasive age-related slowing effects on cognitive performance based on the processing-speed theory (Salthouse, 1996).”

“…a broader review of neurocognitive aging models is beyond the scope of this article (see Anderson & Craik, 2017; Park & Reuter-Lorenz, 2009), age-related declines in inhibitory capacity (Hasher & Zacks, 1988) and reduced speed of processing (Salthouse, 1996) are among the most often cited accounts.”

“This is not surprising, given the evidence that age-related cognitive deficits are particularly evident in these domains (Jolles, 1986; Craik and Jennings, 1992; Moscovitch and Winocur, 1992; Verhaeghen et al., 1993; Salthouse, 1996; Parkin and Java, 2000; Prull et al., 2000).”

“Processing speed declines with age.(46,47) Although researchers have focused on the association between executive dysfunction and daily functional deficits,(48) the present study concurs with recent findings by Wadley and colleagues,(15) who showed that individuals with aMCI differed from healthy controls in speed of…”

“According to resource accounts of behavioral aging, a large variety of the different manifestations of behavioral aging can be reduced to a few causal mechanisms acting as pacemakers of developmental change (cf. Craik, 1983; Craik & Bialystok, 2006; Park & Payer, 2006; Salthouse, 1996).”

“Furthermore, the slowing of basic mental operations might lead to the loss of information (e.g. through mechanisms of decay) by the time it is required for higher-order operations (see Salthouse, 1996).”

“Salthouse, (1996) has argued that age-related slowing is a fundamental mechanism in accounting for age-related decline on many cognitive tasks.”

“…including episodic memory (Zacks et al., 1999; Bäckman et al., 2001), executive functions (West, 1996; Brébion et al., 1997), and perceptual speed (Salthouse, 1996, 1998) also show gradual performance deterioration over the adult life course (for overviews, see Verhaeghen and Salthouse, 1997;…”

“Consistently, many studies evidenced a general age-related decline in executive and attentional functions (Iachini et al., 2009; Lithfous et al., 2013; Salthouse, 1996).”

“One explanation is that age-related increases in neural noise slow down all processes related to evidence accumulation and response selection at the same rate (i.e., the global slowing hypothesis; e.g., Brinley, 1965; Cerella, 1985; Salthouse, 1996).”

“cognitive functions: the sensory deficit theory (Baltes & Lindenberger, 1994); the resources deficit theory (Craik, 1986); the speed deficit theory (Salthouse, 1996); and the inhibition deficit theory (Hasher & Zacks, 1988).”

“The general slowing with age framework (Salthouse, 1996) argues that slowing accounts for much of the age-related variance in performance on complex cognitive tasks.”

“Memory decline in the elderly has also been attributed to cognitive factors such as a reduction in processing speed (Salthouse, 1996) and attentional resources (Craik and Byrd, 1982).”

“General processing speed has been linked to individual differences in many cognitive tasks (e.g. Kail & Salthouse, 1994; Salthouse, 1996).”

“Because of the high reliance of auditory processing on precise timing, auditory processing may prove a sensitive model for testing the ‘Processing speed theory’ of cognitive decline [53], according to which declining processing speed is the common cause of cognitive decline.”

“We focused on accuracy instead of reaction time because reaction time measures are known to reflect a strong processing speed factor (e.g., Fry & Hale, 1996; Li et al., 2004; Salthouse, 1996).”

“This interpretation has been widely accepted (e.g., Birren, 1965; Cerella, 1985, 1990; Cerella, Poon, & Williams, 1980; Fisk & Warr, 1996; Salthouse, 1985, 1996; Salthouse, Kausler, & Saults, 1988) although it has engendered much criticism and debate (Allen, Ashcraft, & Weber, 1992; Allen, Madden, Weber, & Groth, 1993…”

“What cognitive mechanisms underlie this deficit? We have appealed to Salthouse’s simultaneity mechanism of cognitive aging (Salthouse, 1996); because of cognitive slowing, older people have less information available simultaneously than do younger people and so they develop an impoverished mental model (D.”

“Second, age-related variance in r eaction time indices might account for sizeable portions of the variance in more complex cognitive functions (Madden, 2001; Salthouse, 1991, 1996 ).”

“In addition, age-related decline in cognitive performance (Salthouse, 1996) can be ameliorated by factors that affect performance expectations, such as whether there is an instructional emphasis on memory (Rahhal, Hasher & Colcombe, 2001).”

“In addition, measures of speed have repeatedly been found to be closely linked to age-related individual differences in episodic memory functioning and other aspects of fluid intelligence (Bryan & Luszcz, 1996; Lindenberger et al., 1993; Salthouse, 1996; Verhaeghen & Salthouse, 1997) and have been interpreted as prime…”

“Timed tests of reasoning, such as the Alice Heim test, are good measures of processing speed or mental efficiency.(26) Further support for the lack of association with memory comes from studies showing greater effects of inflammatory factors on vascular rather than Alzheimer-type dementia.”

“According to this hypothesis, the main effect of ageing is to slow down all cognitive processes by the same rate (e.g., Brinley, 1965; Cerella, 1985; Salthouse, 1996).”

“However, rather than being due to slower attentional filtering, it is still possible that this effect instead results from a nonspecific age difference in processing speed (e.g., Salthouse 1996).”

“Several authors have argued that processing speed accounts for the relationship between WM and cognitive performance on a multitude of tasks (e.g., Johnston & Anderson, 1998; Kail, 1993; Salthouse, 1996).”

“age-related declines in cognitive ability are related to efficiency of perceptual discrimination, as suggested in the processing speed theory of cognitive ageing.(27) Repeated collection of cognitive and other phenotypic data has also enabled the cohorts to examine putative determinants of cognitive ageing.”

“Several lines of evidence have demonstrated that aging is generally associated with decreased processing speed (e.g., Salthouse, 1986, 1996), reduced sensory acuity (Schneider et al., 2002, 2007; Schneider, Pichora-Fuller, Kowalchuk, & Lamb, 1994; Schneider, Speranza, & Pichora-Fuller, 1998), and…”

“The predominant theories to explain these declines include general cognitive slowing (Salthouse, 1996), inhibitory deficits (Hasher & Zacks, 1988), and task-switching deficits (Mayr & Liebscher, 2001), all of which may have consequences for hazard perception.”

“The list of theories in table 2 is not meant to be exhaustive (see e.g., review of theories in Light 1991; Craik & Jennings 1992; Salthouse 1996; Smith 1996), but will serve to illustrate the significance of the new pattern of spared and impaired functions that must be considered in developing…”

“The middle-age period is often characterized by the onset of such subtle changes in cognitive performance, most notably in executive function and processing speed (32, 53, 54).”

“…of evidence that even healthy older adults experience age-related declines across multiple facets of cognition (Park & Shaw, 1992; Park et al., 1996; Salthouse, 1996; Salthouse & Babcock, 1991), one major goal of interventions is to improve or maintain cognition in order to promote independence…”

“To date, the most influential and empirically tested models in neuropsychology and cognitive literature are the processing speed theory (Salthouse, 1996) and the prefrontal-executive theory (West, 1996).”

“A second view argues that reduced processing speed is a central mechanism in the explanation of age differences in performance (Fisk & Warr, 1996; Salthouse, 1996).”

“This movement gained further momentum by the great success Timothy Salthouse had in using speed as an individual differences variable that accounted for considerable age-related variance on memory tasks (Salthouse, 1985b, 1996).”

“…measures of performance in tasks of this type have been found to share 75% or more of the age-related variance from a variety of cognitive measures, speed of processing has been postulated to be centrally involved in the hypothesized common factor (Salthouse, 1993, 1994b, 1994c, 1996a, 1996b).”

“Consistent with this view, empirical evidence suggests that declines in physical health and basic cognitive functioning become increasingly prevalent in old age (e.g., Baltes & Mayer, 1999; Salthouse, 1996; Schaie, 1989).”

“[18,56, 59] and Park and Gutchess in this issue).”

“Cognitive performance in most domains declines with age, particularly processes such as psychomotor speed; however, some abilities may remain stable or even improve up to a certain age, such as vocabulary (5).”

“To examine the role of age and processing speed on the different measures of executive control (Salthouse, 1996), we first analyzed performance on the color-naming task.”

“…aging models have postulated distributed deficits in specific processes, for example, speed of propagation of excitation in the network (e.g., Salthouse, 1996), aging research has not used models with distributed representations wherein semantic, phonological and orthographic information is…”

“Based on the ubiquity of empirical evidence for negative age-related changes in the domains of both cognitive and motor functioning extant models of cognitive aging [7,46] posit that general slowing of central, cognitive processes is the main cause for these developmental trends.”

“Studies show that older adults tend to display a general slowing in processing speed, a reduction in inhibitory control, and a general decline of attentional resources [73–75].”

“The current results also indicate that the subcomponent processes of shifting, updating, and resistance to proactive interference are distinct from verbal memory, visual memory, and perceptual speed, three other cognitive constructs that are highly affected by aging (Park et al., 2002; Salthouse, 1996).”

“Processing speed being the cognitive measure most strongly associated with age could be seen as supporting the processing speed theory of cognitive aging [43].”

“This research has consistently shown that slower processing speed contributes to at least some of the agerelated differences across a variety of different cognitive variables (Salthouse, 1996).”

“Speed of processing refers to how rapidly people perform mental operations (Salthouse, 1991, 1996), whereas working memory is the on-line processing capacity available to store, retrieve, and manipulate information.”

“One such primitive that has been researched extensively is processing speed (Salthouse, 1991, 1996; Verhaeghen & Salthouse, 1997).”

“These hypotheses include generalized slowing (Cerella, 1985; Myerson, Hale, Wagstaff, Poon, & Smith, 1990; Salthouse, 1996), reduced processing resources (Craik & Byrd, 1982), reduced working-memory capacity (Park, 2000; Salthouse, 1990), inhibitory deficits (Hasher & Zacks, 1988), and disturbed attentional control (B…”

“…suggest that cognitive de- &L E A R N I N G M E M O R Y www.learnmem.org cline with aging is due to decreases in cognitive resources, such as verbal and visuospatial working memory, ability to switch among tasks, inhibitory function, and speed of processing (Salthouse 1996; Park et al. 2002).”

“There are a number of proposed explanations for this decline, including generalized slowing (e.g., Salthouse, 1996) and dedifferentiation (e.g., Wilson et al., 2012).”

“has been shown for example that most of age-related differences in cognition were due to the decrease in the processing-speed (18).”

“operations, which are embedded in the particular task measured (Salthouse, 1996).”

“Several mechanisms have been implicated but the most likely is that older persons are slower to process information (Salthouse 1996).”

“It has been proposed that these deficits are the result of age-related decreases in cognitive functioning (Salthouse, 1996; Howard and Howard, 2001; Howard et al., 2004; Rieckmann and Bäckman, 2009).”

“, 2007), deficits inworking memory (Gordon-Salant and Fitzgibbons, 1997), and reduced speed of processing (Humes, 2007; Salthouse, 1996).”

“Such difficulties would be expected for older adults, where working memory capacity and processing speed are rarely equivalent to that of younger adults (Kausler, 1994; Salthouse, 1994, 1996).”

“cantly to the age-related cognitive decline (20, 21).”

“According to these views there is a stable period of performance followed be an inevitable decline in intellect as the individual reaches middle age and beyond (e.g., Horn, 1982; Horn & Donaldson, 1976; Salthouse, 1996).”

“Second, the overall processing speed decreases (Cerella, 1990; Fisk & Warr, 1996; Myerson, Hale, Wagstaff, Poon, & Smith, 1990; Salthouse 1993, 1996), which hinders the simultaneous activation of mutually referring information elements.”