Adult age differences in the speed and capacity of information processing: 2. An electrophysiological approach

A total of 60 subjects performed different variants of the Sternberg memory search task in an experiment designed to evaluate aging differences in the speed of the human information-processing system. The present study examined the nature of the age-related slowing using convergent methodologies of Sternberg's additive factors logic, the speed-accuracy trade-off, and the P300 component of the event-related brain potential. These methodologies revealed that a substantial component of slowing was manifest in perceptual encoding, response criterion adjustment, and response execution, with a lesser component related to memory search speed.     

Age, information processing speed, and intelligence

Two parallel, but independent, literatures have grown out of observations that individual differences in information processing speed, as expressed in performance on choice reaction time (C RT) tasks, modestly correlate with individual differences in age and IQ test performance. These associations have prompted theories that individual differences in information processing speed functionally determine individual differences in performance of all cognitive skills by people of different general intellectual ability (Eysenck, 1986; Jensen, 1985) or age (Salthouse, 1982, 1985).

The experiments on which this literature has been based suffer from methodological weaknesses, such that comparisons have only been made very early in practice and have only concerned mean latencies for correct responses. An experiment compared 90 volunteers aged from 50 through 79 years who were grouped in terms of their performance on the AH 4 (Heim, 1968) IQ test. It explored the joint and independent effects of individual differences in age and in IQ test score and the effects of practice on mean latencies (C RTs) on the shapes of distributions of correct and incorrect responses and on the limiting speeds with which accurate responses can be made (speed/error trade-off functions). We suggest that a plausible explanation for the results is that individual differences in age and in general ability influence C RTs mainly because they affect the efficiency with which responses can be controlled to maximize speed while maintaining accuracy.     

Age and individual differences in visuospatial processing speed: Testing the magnification hypothesis

Forty young adults and 40 older adults performed seven visuospatial information processing tasks. Factor analyses of the response times (RTs) yielded a single principal component with a similar composition in both age samples. For both samples, regressing the mean RTs of fast and slow subgroups for the seven tasks (18 conditions) on the corresponding mean RTs for their age group accounted for 99% of the variance. Taken together, these findings suggest that individual differences in processing time were largely task independent. The magnification hypothesis, a simple mathematical model of the interaction between age and ability, is presented. This model correctly predicts the finding that in both the young and the older adult groups, individual differences increased systematically with task difficulty. The magnification hypothesis also explains the regression parameters describing individual differences among young adults and predicts correctly that equivalent parameters describe individual differences among older adults. According to the magnification hypothesis, the RTs of slower individuals are more affected by aging than those of faster individuals, and slower individuals may be more at risk with respect to other biological insults (e.g., changes in health status) as well.     

Age differences in dual-task performance after practice

This study investigated whether older adults could acquire the ability to perform 2 cognitive operations in parallel in a paradigm in which young adults had been shown to be able to do so (K. Oberauer & R. Kliegl, 2004). Twelve young and 12 older adults practiced a numerical and a visuospatial continuous memory updating task in single-task and dual-task conditions for 16 to 24 sessions. After practice, 9 young adults were able to process the 2 tasks without dual-task costs, but none of the older adults had reached the criterion of parallel processing. The results suggest a qualitative difference between young and older adults in how they approach dual-task situations.     

Individual differences in learning and memory: A unitary information processing approach

Recent research in the area of individual differences in learning and memory is reviewed from a cognitive perspective. Using the two-state model of memory as a framework, individual variations in attentional, short-term store, and long-term store processes are discussed. The focus is on using individual differences to evaluate nomothetic cognitive models, as well as on using cognitive models in guiding research on individual differences. Both within-individual and between-individual differences in basic processes are examined. In so doing, the importance of strategy choice is stressed using the concept of cognitive flexibility. Several promising directions, both methodological and theoretical, are noted and the value of using specific information processing models in the study of individual differences is emphasized.     

A cross-sequential analysis of developmental differences in speed of visual information processing

Development of processing speed was examined in three backward masking studies. The first verified the central nature of backward masking for children aged 8 and 11 years and for adults. The second suggested that task requirements were equivalent for children similar to those in Study 1, and that age differences in performance were not attributable to nonprocessing variables. The main cross-sequential study estimated speed of processing in 80 children (approximately 6 years to 13 years) and young adults using an inspection time task. Target exposure duration was varied to establish the time required to achieve a high level of discriminative accuracy. Estimates of processing speed increased until about 11-13 years of age; beyond this, the trend was less obvious, and it is possible that inspection time asymptotes at around the onset of adolescence. Performance improvement after 1 year could not be explained as resulting from practice since improvement among controls over a period of 2 weeks was significantly less. Correlations between estimates of inspection time made up to 2 years apart found the measure to be reliable.     

Individual and group differences in intelligence and speed of information processing

A battery of eight different reaction time (RT) tests, measuring the speed with which individuals perform various elementary cognitive processes, and a group test of scholastic aptitude (the Armed Services Vocational Aptitude Battery, ASVAB) were given to 50 black and 56 white male vocational college students. The regression of the general factor scores of the ASVAB on the RT measures yielded a shrunken multiple correlation of 0.465. Although discriminant analyses, when applied separately to the ASVAB subtests and to the RT variables, showed highly comparable overall discrimination (over 70% correct classification) between the black and white groups, factor scores derived from the general factor (labeled ‘speed of information processing’) of the RT battery show only about one-third as large a mean black-white difference as the mean group difference on the general factor scores derived from the ASVAB. Comparisons were also made between the 106 vocational college students and 100 university students of higher average academic aptitude who had previously been tested on the same RT battery (Vernon, 1983a). These groups showed marked differences on the RT variables, the largest differences occuring on the tests that required more complex cognitive processing. The more complex RT tests also correlate most highly with the psychometric measures of ability within each group. The results are consistent with the hypothesis that individual differences and the mean differences between groups in psychometric abilities and scholastic achievement are related to differences in the speed of information processing as measured in elementary cognitive tasks.     

Age differences in dual-task interference are localized to response-generation processes

Dual-task differences in younger and older adults were explored by presenting 2 simple tasks, with the onset of the 2nd task relative to the 1st task carefully controlled. The possibility of an age-related reduction in the ability to generate and execute 2 similar motor programs was explored by requiring either a manual response to both tasks or a manual response to the 1st and an oral response to the 2nd and was confirmed by the evidence. The age-related interference was greater than would be expected from a general slowing of processing in older adults. The possibility of an age-related reduction in the capacity to process 2 tasks in the same perceptual input modality was explored by presenting both tasks in the visual modality or the 1st task in the auditory modality and the 2nd task in the visual modality and was not supported by the evidence. There was greater interference when both tasks were in the same modality, but it was equivalent for older and younger adults. Age differences in dual-task interference appear quite localized to response-generation processes.     

Gender and priming differences in speed of processing of information relating to social structure

Previous research has shown that women and men’s different interactional contexts result in selective differences in retention of information (e.g., Gabriel & Gardner, 1999). This study tested the hypothesis that there should be broad gender-related differences in latencies of retrieval of information focused on groups or dyads, with women processing the latter more rapidly, and men processing the former more rapidly. Participants were given a diary reading task with explicit recall instructions. Results showed that although no difference was found in overall retention of items, women responded more rapidly to items referring to dyads, while men responded more rapidly to items referring to groups. In addition, a strong effect of the gender of the protagonist of the diary was found. Participants of both gender responded more rapidly to dyadic items when the protagonist was female but responded more rapidly to group items when the protagonist was male. These results indicate that gender differences in social structure result in differences in encoding and retrieval of broad classes of information that are not accountable for by selective retention.     

Cultural differences in the development of processing speed

The aim of the present work was to examine cultural differences in the development of speed of information processing. Four samples of US children (N = 509) and four samples of East Asian children (N = 661) completed psychometric measures of processing speed on two occasions. Analyses of the longitudinal data indicated that, although processing speed was comparable among US and East Asian children at the youngest age (~4.5 years), it developed more rapidly in some but not all of the East Asian samples. Results are discussed in terms of factors that may promote more rapid development of processing speed in some East Asian cultures.     

Sex differences in information processing

Sex differences in cognitive activity were investigated. Using a list containing words with masculine, feminine, and neutral connotations, Experiment 1 revealed that masculine words were better recalled by male college students (n=16) while feminine words were better recalled by female college students (n=16). This difference was reduced on a recognition test. Experiment 2 demonstrated that the phenomenon was not due to a difference in the way males (n=20) and females (n=20) interpreted the meaning of the words. Finally, in Experiment 3, the memorial selectivity was shown to exist in the same manner for White middle-class elementary school (n=32) and high school (n=32) students. Learning and repression interpretations of the effect were proposed. Some practical implications of the data were suggested.These investigations were supported by a seed grant to the first author. This grant was jointly funded by Southern Methodist University and the National Science Foundation's Institutional Grants for Science Program (GU-3752). The authors would like to express their appreciation to the pupils and teachers on Fain Elementary School and Rider High School, both in Wichita Falls, Texas.     

The differences between cerebral dominance patterns in the speed and accuracy of information processing among university students

IntroductionThe subject of cerebral dominance has received great attention by researchers; however, there is a paucity of studies that have examined its relationship to information processing.ObjectiveThe current study aims to reveal the differences between the cerebral dominance patterns (left cerebral dominance, right cerebral dominance, integrated parallel cerebral dominance) in the speed and accuracy of information processing.MethodA sample of (182) volunteers university students, (mean age ± SD, 19.92 ± 2.76 years; range, 18–24 years; 68 male, 114 females). The Human Information processing survey was applied to the participants. Each subject was exposed to two elementary cognitive tasks (Stroop task and Eriksen flanker task). Each task included two experimental conditions: first, the congruent condition that reflects the automatic processing of information; second, the incongruent condition that reflects the controlled processing of information.ResultsThe results of the study revealed that there were no differences between the patterns of cerebral dominance in the speed and accuracy of information processing.ConclusionAlthough the relationship between cerebral dominance and information processing is not significant, we need more studies to examine this relationship in other samples and in other experimental conditions.     

Developmental differences in the allocation of processing capacity

Recently psychologists have formulated a comprehensive view of attention involving allocation of processing capacity. Although developmental changes in processing capacity have been proposed as one source of age differences in certain cognitive skills, there has been little systematic investigation of this hypothesis. In the present study, second and sixth graders and adults (8, 12, and 20 years of age, respectively) performed a letter-matching task (primary task) concurrently with an auditory detection task (secondary task). Changes in reaction time in the secondary task as a function of manipulations of the primary task were used to estimate capacity allocation to the primary task. Primary task variables included stage of processing (alerting, encoding, rehearsing, responding) and matching condition (physical-identity vs name-identity matching). Age differences in secondary task performance were found to be related to stage of processing but not to matching condition. Earlier stages of the letter match task (alerting, encoding) required somewhat more capacity allocation in younger subjects. Later stages (rehearsing, responding) made substantially higher demands on capacity in children. Capacity allocation may be an important cognitive variable mediating developmental differences in basic information processing skills, and may underlie age trends found in performance of certain complex cognitive tasks.     

Age and the selectivity of visual information processing

Two experiments were conducted to assess age differences in the selectivity of visual information processing. Selectivity was measured by the amount of interference caused by nontarget letters when subjects detected a target letter in a visual display. In both experiments, young and elderly groups participated in search and nonsearch conditions; in the search condition targets appeared anywhere in the display, whereas in the nonsearch condition targets were confined to the center position of the display. In the first experiment, subjects were assigned to either condition for two sessions of testing, and in the second experiment each subject participated in both conditions. In both experiments nontargets produced larger interference effects for old compared to young adults in the search condition but not in the nonsearch condition. The obtained pattern of age effects could not be explained by age-related reductions in parafoveal acuity. The findings indicate that the magnitude of divided-attention deficit increases with age, whereas focused-attention deficits are unaffected by aging.     

Raven's matrices and working memory: A dual-task approach

The cognitive system does not just act as a mirror from the sensory input; instead, it tends to normalize this information. Given that letter processing seems to be much more specialized than digit processing in the cortex, we examined whether the regularization process occurs differently from digits to letters than from letters to digits: We employed a masked priming same/different experiment (e.g., probe, VESZED; prime, V35Z3D ; and target, VESZED). When embedded in letter strings, digits that resemble letters (e.g., 3 and 5 in V35Z3D -VESZED) tend to be encoded in a letter-like manner, whereas when embedded in digit strings, letters that resemble digits (e.g., E and S in 9ES7E2–935732) tend not to be encoded in a digit-like manner.     

Misleading postevent information and working memory capacity: an individual differences approach to eyewitness memory

The present study examines how individual differences in working memory capacity relate to the effect of misleading postevent information on memory for the original event. Participants were shown a film of a crime event and were then asked to unscramble a narrative that included misinformation regarding some of the film's details. Additionally, the working memory capacity of the participants was measured using the operation‐word span task. Finally, in a free recall test, participants recalled fewer correct details in the misinformation condition compared to the control condition. This effect was negatively correlated with working memory capacity. Copyright © 2002 John Wiley & Sons, Ltd.     

Different attentional blink tasks reflect distinct information processing limitations: an individual differences approach

To study the temporal dynamics and capacity-limits of attentional selection and encoding, researchers often employ the attentional blink (AB) phenomenon: subjects' impaired ability to report the second of two targets in a rapid serial visual presentation (RSVP) stream that appear within 200-500 ms of one another. The AB has now been the subject of hundreds of scientific investigations, and a variety of different dual-target RSVP paradigms have been employed to study this failure of consciousness. The three most common are those where targets are defined categorically from distractors; those where target definition is based on featural information; and those where there is a set switch between T1 and T2, with the first target typically being featurally defined and T2 requiring a detection or discrimination judgment (probe task). An almost universally held assumption across all AB theories is that these three tasks measure the same deficit; however here, using an individual differences approach, we demonstrate that AB magnitude is only related across categorical and featural tasks. Thus, these paradigms appear to reflect a distinct cognitive limitation from that observed under set-switch conditions.     

Age and skilled performance: contributions of working memory and processing speed

In this study, we examined the interrelationships among age, working memory (WM), processing speed, and the development of skilled performance. Younger (M=20.5) and older (M=68.9) adults were trained on an alphabet arithmetic task (Haider & Frensch, 1996) administered across three consecutive days. Although older adults were slower than younger adults, both age groups' response latencies decreased as a result of practice. Contrary to expectations, WM and processing speed were significantly correlated with performance late in training. Partial correlations suggested that age differences in performance at the end of training were mediated by individual differences in cognitive processing speed.     

Age and exposure differences in acquisition of route information

Age and exposure differences were studied in the acquisition of sequentially ordered spatial information and in memory for critical route events. Ss in 4 age groups (older adults, middle-aged adults, college students, and adolescents) viewed slides depicting 2 overlapping neighborhood routes either 1 or 3 times. Older adults were less likely to recall landmarks sequentially and were more likely to recall nonspatial associations to the routes and to regard salient landmarks (rather than turns) as critical route-maintaining events. Exposure was related to number of landmarks recalled, route scene assignment, and reason for selecting critical scenes and was marginally related to critical scene selection. The results suggest that landmark saliency may relate to route learning for older adults, influencing both encoding organization and evaluation of environmental events. The role of decline in cognitive capacity, and the tendency to encode general vs. specific aspects of complex episodic experiences, are discussed.