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.     

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.     

The relationship between morningness–eveningness, time-of-day, speed of information processing, and intelligence

Morningness–Eveningness refers to individual differences in circadian phase position of spontaneous sleep–wake rhythms and to subject alertness. There is some evidence indicating that performance on cognitive tasks may be influenced by Morningness–Eveningness and time-of-day. Given the potential importance of such a finding for the assessment of cognitive ability we conducted a study assessing the relationship between Morningness–Eveningness, time-of-day, and performance on the Multidimensional Aptitude Battery IQ (MAB-IQ) and Inspection Time (IT) task. Twenty male and 50 female participants classified according to their scores on the Morningness–Eveningness dimension (Horne & Östberg, 1976) were administered the MAB and IT tasks in the morning (0900 h) and in the late afternoon (1500 h). No significant effect of time of testing, and Morningness–Eveningness was observed except for the Spatial subtest of the MAB. Morning Type-participants performed significantly worse in the morning session in Spatial subtest and better in the late afternoon session and Evening Type-participants performed significantly better in the morning than in the late afternoon session. These results do not support the hypothesis that there is a reliable relationship between Morningness–Eveningness, time-of-day and cognitive ability.     

Visual information processing and intelligence

Measures of inspection time (IT) have robust, moderately-sized correlations with IQ-type test scores. However, the reason for the IT-IQ correlation is not understood. Although the original theory asserted that IT performance was based on a single parameter—essentially speed of visual processing—peculiarities of the task have afforded other interpretations of IT differences and the IT-IQ association. In the present report two new visual processing tasks, visual change detection (VCD) and visual movement detection (VMD) are found to be correlated at or above .4 with IT and with non-verbal scores from the Alice Heim 4 test of general intelligence. VCD and VMD, in common with IT, assess the stimulus duration that is required by subjects in order to make an accurate discrimination. VCD and VMD, however, require a broader attentional focus than IT and do not involve backward masking. Measures of contrast sensitivity, a difficult discrimination task in which stimuli are not time-limited, had near-to-zero correlations with other visual processing tasks and with IQ-type test scores. We tested the hypothesis that only the latent trait derived from the speeded visual processing tasks (rather than task-specific features) would correlate with cognitive ability, and this was supported. The present study adds weight to the view that it is the ability to make accurate discriminations in the face of limited stimulus time that causes IT to correlate with psychometric intelligence. The psychological correlates of VCD, in terms of neural circuits that detect “difference” suggest a new line of investigation into the psychobiological bases of human intelligence.     

Speed of information processing and general intelligence

This study investigates the relationship between a number of measures of speed of cognitive information-processing and intelligence test scores. One hundred university students were given five tests of speed-of-processing, measuring their speed of encoding, short-term memory scanning, long-term memory retrieval, efficiency of short-term memory storage and processing, and simple and choice reaction time or decision-making speed. They were also given the Wechsler Adult Intelligence Scale and the Raven Advanced Progression Matrices. A number of multiple regression analyses show that the cognitive processing measures are significantly related to IQ scores. Other analyses indicate that this relationship cannot be attributed to the common content shared by the reaction time and the intelligence tests, nor to the fact that parts of the WAIS are timed. It is concluded that the reaction time tests measure basic cognitive operations which are involved in many forms of intellectual behavior, and that individual differences in intelligence can be attributed, to a moderate extent, to variance in the speed or efficiency with which individuals can execute these operations.     

Visual,auditory and reaction time approaches to the measurement of speed of information processing and individual differences in intelligence

A battery of tachistoscopic, auditory, reaction time and microcomputer-generated measures of speed of information processing (inspection time, IT) were administered to 96 college students aged between 18 and 22 yr. In addition, each S was given a battery of tests designed to provide independent evaluations of right- and left-hemispheric functioning. Criterion measures included a verbal (Vocabulary) and a nonverbal (Block Design) measure of intelligence. Results revealed a general processing speed factor in addition to task-specific sources of variability. Moreover, the IT tasks loaded on the same second-order factor as did the traditional measures of intelligence and aptitude. The findings support the theoretical view that processing speed may be a general factor in individual differences in performance on complex intellectual solving tasks. An important objective for future work in this area is to seperate and evaluate the common and specific sources of variability on IT tasks.     

Speed of emotional information processing and emotional intelligence

The present study aimed to investigate the relationship between the speed of emotional information processing and emotional intelligence (EI). To evaluate individual differences in the speed of emotional information processing, a recognition memory task consisted of two subtests similar in design but differing in the emotionality of the stimuli. The first subtest required judgment about whether an emotional facial expression in the test face was identical to one of the four emotional expressions of the same individual previously presented. The second subtest required deciding whether the test face with a neutral emotional expression was identical to one of the four neutral faces of different individuals previously presented. Mean response latencies were calculated for “Yes” and “No” responses. All latencies were correlated with other measures of processing speed such as discrimination time and time of figure recognition. However, the emotional expression recognition subtest was hypothesized to require the processing of emotional information in addition to that of facial identity. Latencies in this subtest were longer than those in the face recognition subtest. To obtain a measure of the additional processing that was called for by the emotionality of the stimuli, a subtraction method and regression analysis were employed. In both cases, measures calculated for “No” responses were related to ability EI, as assessed via a self‐report questionnaire. According to structural equation modeling, there was a moderately negative association between latent EI and the latency of “No” responses in the subtest with emotional stimuli. These relationships were not observed for “Yes” responses in the same subtest or for responses in the subtest with neutral face stimuli. Although the differences between “Yes” and “No” responses in their associations with EI require further investigation, the results suggest that, in general, individuals with higher EI are also more efficient in the processing of emotional information.     

Relations between information processing and intelligence in elderly adults

Measures of verbal intelligence and abstract reasoning were taken on a group of 31 college-aged and 32 elderly adults, together with mental-processing rates associated with choice reaction time, primary memory scanning, and lexical decoding. Group means showed that both verbal IQ and lexical decoding were intact in the elderly subjects, a relationship in keeping with theorizing of Hunt (1978). In contrast, there were large declines in both Ravens scores and a variety of CRT measures, in keeping with theorizing of Jensen (1980). The group results were upheld at the level of individual subjects in the verbal domain, but in the case of CRT, only intercept values, not slopes, correlated with abstract reasoning. Memory-scanning rates were unrelated to intelligence measures.     

Associative learning predicts intelligence above and beyond working memory and processing speed

Recent evidence suggests the existence of multiple cognitive mechanisms that support the general cognitive ability factor (g). Working memory and processing speed are the two best established candidate mechanisms. Relatively little attention has been given to the possibility that associative learning is an additional mechanism contributing to g. The present study tested the hypothesis that associative learning ability, as assessed by psychometrically sound associative learning tasks, would predict variance in g above and beyond the variance predicted by working memory capacity and processing speed. This hypothesis was confirmed in a sample of 169 adolescents, using structural equation modeling. Associative learning, working memory, and processing speed all contributed significant unique variance to g, indicating not only that multiple elementary cognitive processes underlie intelligence, but also the novel finding that associative learning is one such process.     

Visual information processing speed in hypnotized and nonhypnotized subjects

Using a backward-masking paradigm with a bias-free and ceiling-free psychophysical task, we tested hypnotized and control subjects for speed of visual information processing. Approximately half of each group received visual imagery suggestions in an attempt to influence attention. Imagery produced no significant differential effect. Although an absence of a hypnotizability-performance relationship was in keeping with findings of a previous study, those subjects in the present study who performed under hypnosis were, as a group, significantly superior to the other subjects in speed of information processing.     

The relationship between speed of information processing and cognitive ability

Speed of information processing as measured by various reaction time and inspection tasks has been shown to correlate with psychometric intelligence, and it has been suggested that general intelligence (g) is determined to some degree by the speed that information is processed. If this is so, then various measures of speed of information processing should correlate substantially with each other, and each should also correlate with a wide range of psychometric tests that load on g. Alternatively, intelligence may be considered to be a multi-faceted complex of partially related abilities with specific abilities being dependent upon specific cognitive processes. If this is the case, it should be possible to discover independent cognitive processes, some of which correlate with one facet or broad ability and some with another. This paper presents three experiments in which the relationship between intellectual ability and four speed of information processing measures was examined. These were rate of memory scanning, rate of retrieval of information from long term memory, speed of stimulus-response mapping and inspection time (IT). Results showed that correlations between IT and most reaction time measures of speed of information processing were low, and that correlations between different versions of IT were negligible. In addition, some cognitive tasks with verbal material (memory scanning rate for digits and Posner letter matching IT) correlated most substantially with Verbal Reasoning whereas non-verbal (two-line) IT consistently correlated with tests loading on g. It was thus suggested that while non-verbal IT may be a measure of a perceptual speed attribute that contributes to mental functioning, other “speed of information processing” parameters may be more specific to a subset of abilities.     

The relationships of basic information processing measures with fluid and crystallized intelligence

The aim of the present research is to study the nature of Basic unit of Information Processing (BIP) by means of two related experiments. The first of these experiments uses structural equation models to attempt to confirm the relationships between these measures and crystallized intelligence proposed by Draycott and Kline (Personality and Individual Differences, 20, 201–210, 1994). The second attempts to find out more about the relationships between this and other Chronometrie measures both in computer and paper and pencil administration. Results seem to confirm the relationship between BIP and crystallized intelligence and it seems to be extensive to other paper and pencil measures such as the visual forms test. The relationships between task complexity and the size of the correlation between Chronometric measures and intelligence are also discussed.     

Temporal information processing and pitch discrimination as predictors of general intelligence.

In the present study, the relationship between performance on temporal and pitch discrimination and psychometric intelligence was investigated in a sample of 164 participants by means of an experimental dissociation paradigm. Performance on both temporal and pitch discrimination was substantially related to psychometric intelligence (r=.43 and r =.39). Regression analysis and structural equation modeling suggested that both psychophysical domains can be considered as valid predictors of psychometric intelligence. Both predictor variables contributed substantial portions of both shared and unique variance to the prediction of individual differences in psychometric intelligence. Thus, the present study yielded further evidence for a functional relationship between psychometric intelligence and temporal as well as pitch discrimination acuity. Eventually, findings are consistent with the notion that temporal discrimination - in addition to general aspects of sensory discrimination shared with pitch discrimination reflects specific intelligence-related aspects of neural information processing.     

Performance on auditory and visual temporal information processing is related to psychometric intelligence

The present study investigated the relationship between psychometric intelligence and temporal resolution power (TRP) as simultaneously assessed by auditory and visual psychophysical timing tasks. In addition, three different theoretical models of the functional relationship between TRP and psychometric intelligence as assessed by means of the Adaptive Matrices Test (AMT) were developed. To test the validity of these models, structural equation modeling was applied. Empirical data supported a hierarchical model that assumed auditory and visual modality-specific temporal processing at a first level and amodal temporal processing at a second level. This second-order latent variable was substantially correlated with psychometric intelligence. Therefore, the relationship between psychometric intelligence and psychophysical timing performance can be explained best by a hierarchical model of temporal information processing.     

The roles of working memory updating and processing speed in mediating age-related differences in fluid intelligence

This study was conducted to investigate the relative roles of working memory updating (updating) and processing speed in mediating age-related differences in fluid intelligence. A sample of 142 normal adults between 18 and 85 years of age performed a set of updating, processing speed, and fluid intelligence tasks. Hierarchical regression analyses indicated that the proportion of unique age-related variance in updating measures was related to the complexity of speed measures. There was a larger proportion of unique age-related variance in updating measures after controlling for the variance in simpler speed measures. Moreover, structural equation modeling showed that updating mediated almost all the age-related effects on fluid intelligence. These results suggest that updating, but not speed, is the critical mediator between age and fluid intelligence. In addition, the speed mediation of age-related differences in fluid intelligence as indicated by previous studies is at least partially derived from the executive component of speed measures.     

Modularity,mental retardation and speed of processing

This paper briefly outlines Anderson's (1992) theory of the minimal cognitive architecture underlying intelligence and development and briefly discusses its application to understanding mental retardation and specific cognitive deficits. An experiment on the relationship between face perception and mental retardation serves as an illustration of how the theory might be informative about the relationship between intelligence and cognitive architecture.     

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.     

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.     

Experiential and rational processing styles,emotional intelligence and wellbeing

This research examined a model specifying precursors of emotional intelligence and subjective wellbeing. The model proposes that experiential and rational processing styles influence level of trait emotional intelligence, which in turn influences subjective wellbeing. One hundred and fifty‐four adult Australian participants completed measures of preference for rational and experiential processing, trait emotional intelligence, and indicators of subjective wellbeing (affect and life satisfaction). Structural equation path analysis identified a model for predicting wellbeing. Preference for experiential and rational processing both significantly predicted higher levels of emotional intelligence, which in turn predicted greater subjective wellbeing. Emotional intelligence fully mediated the effect of rational processing on wellbeing, and partially mediated the effect of experiential processing.