Glen Smith

University of Adelaide · School of Psychology

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique which provides unique potential to directly improve human capability on a temporary, at needs, basis. The purpose of this paper is to consider the utility of tDCS through analysis of the potential risks and benefits in the context of defence service personn...

We present a framework for designing and evaluating systemically-robust and efficient hybrid (human and machine) decision networks. We propose the degree of diversity for enterprise variables be chosen according to the expected demands of the decision scenario, with margins for risk and uncertainty. We illustrate the use of the model by comparing t...

This paper draws attention to some of the problems associated with studies of reaction time and intelligence. The experiment reported here used choice reaction time without a home key and was concerned with the relationship between rate of reduction of uncertainty (RRU) and a verbal measure of intelligence (ML) developed for Australian adolescents....

Traditionally the domain of humans, Command and Control (C2) increasingly necessitates the use of automated decision aids and automated decision makers to assist in managing the complexity and dynamics of modern military operations. We propose a blueprint based on the US Joint Directors of Laboratories (JDL) model, cognitive psychology and agent re...

Architectural guidance for the development of fusion and resource management systems exists, yet the automated management of their policies remains nascent in the Joint Directors of Laboratories (JDL) model. We present an architecture to assist design of fusion and Command and Control (C2) systems grounded in an understanding of human intent and Ar...

Political scientist Professor Bruce Bueno De Mesquita, has made significant claims for the predictive accuracy of his computational model of group decision making, receiving much popular press, including newspaper articles, books and a television documentary entitled 'The New Nostradamus'. Despite these and many journal and conference publications...

The decision time/movement time (DT/MT) measures which are obtained when using reaction-time apparatus incorporating a home key are being used to investigate a wide range of group differences. It is usually assumed that the time from stimulus onset to release of the home key is a good measure of central processing speed. It is argued that it is not...

As part of a large ongoing project, the Memory, Attention and Problem Solving (MAPS) study, we investigated whether genetic variability explains some of the variance in psychophysiological correlates of brain function, namely, the P3 and SW components of event-related potentials (ERPs). These ERP measures are minute time recordings of brain process...

There is ongoing debate whether the efficiency of local cognitive processes leads to global cognitive ability or whether global ability feeds the efficiency of basic processes. A prominent example is the well-replicated association between inspection time (IT), a measure of perceptual discrimination speed, and intelligence (IQ), where it is not kno...

The sources of covariation among cognitive measures of Inspection Time, Choice Reaction Time, Delayed Response Speed and Accuracy, and IQ were examined in a classical twin design that included 245 monozygotic (MZ) and 298 dizygotic (DZ) twin pairs. Results indicated that a factor model comprising additive genetic and unique environmental effects wa...

Information processing speed, as measured by elementary cognitive tasks, is correlated with higher order cognitive ability so that increased speed relates to improved cognitive performance. The question of whether the genetic variation in Inspection Time (IT) and Choice Reaction Time (CRT) is associated with IQ through a unitary factor was addresse...

The phenotypic and genetic factor structure of performance on five Multidimensional Aptitude Battery (MAB) subtests and one Wechsler Adult Intelligence Scale-Revised (WAIS-R) subtest was explored in 390 adolescent twin pairs (184 monozygotic [MZ]; 206 dizygotic (DZ)). The temporal stability of these measures was derived from a subsample of 49 twin...

Older adults report self-regulating their driving habits but little is known about factors associated with driving habits and driving confidence. We aimed to evaluate cognitive performance, biomarkers and self-reported sensory function as correlates of self-reported driving behaviour and confidence. A volunteer sample of 153 drivers aged between 60...

The efficacy of psychological treatments emphasising a self-management approach to chronic pain has been demonstrated by substantial empirical research. Nevertheless, high drop-out and relapse rates and low or unsuccessful engagement in self-management pain rehabilitation programs have prompted the suggestion that people vary in their readiness to...

The P3(00) event-related potential (ERP) component is widely used as a measure of cognitive functioning and provides a sensitive electrophysiological index of the attentional and working memory demands of a task. This study investigated what proportion of the variance in the amplitude and latency of the P3, elicited in a delayed response working me...

Individual differences in the variance of event-related potential (ERP) slow wave (SW) measures were examined. SW was recorded at prefrontal and parietal sites during memory and sensory trials of a delayed-response task in 391 adolescent twin pairs. Familial resemblance was identified and there was a strong suggestion of genetic influence. A common...

The genetic relationship between lower (information processing speed), intermediate (working memory), and higher levels (complex cognitive processes as indexed by IQ) of mental ability was studied in a classical twin design comprising 166 monozygotic and 190 dizygotic twin pairs. Processing speed was measured by a choice reaction time (RT) task (2-...

Using the classical twin design, this study investigates the influence of genetic factors on the large phenotypic variance in inspection time (IT), and whether the well established IT-IQ association can be explained by a common genetic factor. Three hundred ninety pairs of twins (184 monozygotic, MZ; 206 dizygotic, DZ) with a mean age of 16 years p...

A multidisciplinary collaborative study examining cognition in a large sample of twins is outlined. A common experimental protocol and design is used in The Netherlands, Australia and Japan to measure cognitive ability using traditional IQ measures (i.e., psychometric IQ), processing speed (e.g., reaction time [RT] and inspection time [IT]), and wo...

Amultidisciplinary collaborative study examining cognition in a large sample of twins is outlined. A common experimental protocol and design is used in The Netherlands, Australia and Japan to measure cognitive ability using traditional IQ measures (i.e., psychometric IQ), processing speed (e.g., reaction time [RT] and inspection time [IT]), and wor...

Performance measures on a coincidence timing task have previously been associated with psychometric IQ suggesting that the ability of an individual to devote processing resources at the required time may account for some of intelligence test variance. Using the twin design, this study investigates whether genetic variability explains some of the va...

Intelligence (IQ) can be seen as the efficiency of mental processes or cognition, as can basic information processing (IP) tasks like those used in our ongoing Memory, Attention and Problem Solving (MAPS) study. Measures of IQ and IP are correlated and both have a genetic component, so we are studying how the genetic variance in IQ is related to th...

In this study a structural equation model of predictors of age differences in cognitive performance in late adulthood was developed. Biological markers of aging (vision, hearing, vibration sense, forced expiratory volume, and grip strength) were used as indicators of a latent variable called BioAge. A sample of 180 community-dwelling women aged 60...

To investigate the test-retest stability of a standardized version of Nelson's (1976) Modified Card Sorting Test (MCST) and its relationships with demographic variables in a sample of healthy older adults. A standard card order and administration were devised for the MCST and administered to participants at an initial assessment, and again at a sec...

Relationships were examined between patients' negative symptoms, family caregivers' knowledge of schizophrenia, caregivers' attributions about the cause of patients' symptoms, and caregivers' response to the symptoms. A sample of 84 caregivers of patients with schizophrenia in Brisbane, Australia, were interviewed using a structured format and meas...

Cerebral responses to alternating periods of a control task and a selective letter generation paradigm were investigated with functional Magnetic Resonance Imaging (fMRI). Subjects selectively generated letters from four designated sets of six letters from the English language alphabet, with the instruction that they were not to produce letters in...

A 74 year old patient, EW, with dorsolateral frontal cortical compression due to hyperostosis frontalis interna, in the absence of the Morgagni or Stewart-Morel syndromes, is described. In addition to conventional neuropsychological measures EW was administered one nonspatial and two spatial self ordered working memory tasks, as well as a standard...

We report test-retest reliabilities for a battery of tests (vision, hearing, vibration sense, proprioception, forced expiratory volume, blood pressure, grip strength, and sway) shown previously to predict functional age. Fifty women aged 60 to 86 were retested on the battery after 3 months. All tests except proprioception and blood pressure had rel...

Monitoring accuracy during choice RT allows subjects to maintain fast, safe RT bands and avoid overly fast, unsafe RT bands. 5 retarded adults received trial-by-trial feedback on accuracy over a number of sessions to train monitoring of accuracy and to improve RT performance. Training was introduced according to a multiple-baseline-across-subjects...

A review of empirical functional age studies published in English was conducted. Types of biomarkers used in functional age studies included sensorimotor, cognitive, psychosocial, behavioral, anthropometric, biomedical, physiological, and dental variables. Previous criticisms of the validity and utility of functional age research were evaluated wit...

The present study compared IQs and Verbal-Performance IQ discrepancies estimated from two seven-subtest short forms of the Wechsler Adult Intelligence Scale-Revised (WAIS-R) in a sample of 100 subjects referred for neuropsychological assessment. The short forms of Warrington, James, and Maciejewski (1986) and Ward (1990) yielded similar correlation...

Young and older adults' mechanisms of trial-by-trial control of accuracy and choice reaction times (RTs) were compared in 2,000 trials. With equal mean error rates, the older group's correct and error RT were longer, and their within-subject distribution was a linear function of the younger group's. Conditional accuracy functions (CAFs) were very s...

Young and older adults' mechanisms of trial-by-trial control of accuracy and choice reaction times (RTs) were compared in 2,000 trials. With equal mean error rates, the older group's correct and error RT were longer, and their within-subject distribution was a linear function of the younger group's. Conditional accuracy functions (CAFs) were very s...

An empirical study examining the personality profile of musicians was conducted on an Australian sample of performers. Personality differences (a) between performing musicians and a nonmusician comparison group, (b) between male and female musicians, and (c) among musicians of five instrumental families were examined. Form A of the 16 Personality F...

A model of cognitive slowing is proposed with the following assumption: Information is lost during processing, processing occurs in discrete steps with step duration inversely related to the amount of information currently available, and the effect of aging is to increase the proportion of information lost per step. This model correctly predicts a...

Brewer and Smith (1984) showed that control mechanisms mediating speed-accuracy regulation contribute to retarded-nonretarded differences in processing speed, with poorly controlled trial-to-trial RT adjustments underlying the greater RT variability of retarded individuals. In Experiment 1, response deadlines controlled processing time, thus minimi...

A model of cognitive slowing is proposed with the following assumptions: Information is lost during processing, processing occurs in discrete steps with step duration inversely related to the amount of information currently available, and the effect of aging is to increase the proportion of information lost per step. This model correctly predicts a...

Particular measures from choice reaction time (RT) are sometimes significantly correlated with intelligence test scores and sometimes not. Several reasons are advanced that may account for this variation. Broadly speaking it is pointed out that subjects may not be responding at their fastest efficient speed in some RT conditions because too few tri...

We investigated the possibility that marked improvements in speed of information processing from early childhood to adulthood reflect improved speed–accuracy monitoring and regulation. Trial-by-trial examination of reaction time (RT) and accuracy transitions during serial choice RT performance revealed developmental changes in accuracy monitoring a...

Two measures of temporal processing: critical stimulus duration (CSD) and visual backward masking (VBM), were examined in a group of normal subjects whose predisposition to psychosis was assessed using the psychoticism (P) scale from Eysenck's Personality Questionnaire. The current study employed the method of constant stimuli with a two-alternativ...

Two independent data sets were selected to examine the interrelations among reaction time (RT), between-subject variability or diversity (SD), and age. In both data sets, a strong correlation between RT and SD was obtained. This strong correlation was not affected when age was controlled in a partial correlation analysis. On the other hand, a weake...

The relationship between corresponding latencies of old and young adults early in practice are examined across a range of tasks (choice reaction time, memory scanning and classification) in a within-subjects design. These relations are well described by linear functions in the case of cognitive processing times (CTs) on all tasks, movement times (M...

A simple tailored version of the California Psychological Inventory (CPI) was derived from the responses of a calibrating sample of 1,190 subjects using an approach based on a one-parameter item-response theory. This tailored version was administered on a microcomputer to a second independent sample. Validity data were obtained separately from the...

It is argued that if a response time (RT) measure correlates with psychometric test (PT) scores because it shares variance in common with general intelligence, g, then the profile of g loadings for a set of PTs would be predictable from the profile of correlations between the RT measure and the PT scores. On the other hand, if an RT correlates with...

Timed performance measures from a coincidence timing (CT) task taking about 10 minutes are shown to have significant correlations with psychometric general intelligence in a group of 56 children. This task required subjects to press a key when a moving target is coincident with a stationary line. The mean absolute error across three conditions (CTE...

The effects of varying stimulus duration on two response measures, percentage correct (pc) and mean reaction time (RT) were investigated in a lights-keys RT task similar to an inspection time (IT) task. One of either N = 2, 4 or 8 lights came on as the stimulus, followed after a range of stimulus exposure durations (D) by all 8, as a backward mask....

The scores of 475 managers on the primary scales of 16PF, form A. were analysed and converted to age-corrected whole unit normalized stens (n-stens). Additionally, the first eight second order factors were calculated and presented as n-stens. It is suggested that these norms will be useful for future research on personality and aspects of managemen...

Rabbitt (1979, 1981) has argued that the slowing of choice RT performance with old age reflects less sensitive control over speed of responding. Based on the finding that old subjects' errors were as fast as young subjects', whereas their correct responses were much slower, Rabbitt suggested that old subjects often overshoot when trying to increase...

Brewer and Smith in 1984 reported pre- and posterror RT data indicating that fast, accurate responding on a visual, four-choice RT task is mediated by a trial-by-trial tracking mechanism such as outlined by Rabbitt recently. In this study the generality of this account was examined by testing subjects on visual or vibrotactile choice-RT tasks (two-...

Two experiments, with 34 mentally retarded (MR) 16-33 yr olds (WAIS IQs 43-76) and 34 CA-matched normal controls, investigated whether differences in the way that MR and non-MR monitor and regulate speed and accuracy of responding contribute to the slower and more variable performance of MR Ss on choice RT tasks. In Exp I, most MR Ss detected their...

The relationships between intelligence test scores and measures derived from reaction time (RT) and perceptual speed procedures were investigated in 137 twelve-year-old students with IQs ranging from 59 to 142. A range of intelligence tests were used and the scores factor analyzed to produce general, spatial and verbal factors. Test and factor scor...

The efficiency of eye-movements while tracking sequential lights was compared for 15 dyslexic children and 15 controls, matched on age and non-verbal intelligence. Contrary to Pavlidis (1981), no significant differences were found between the two groups on two measures of efficiency. A hierarchical cluster analysis did not demonstrate unique patter...

One of the difficulties facing any attempt to investigate a research finding is to know what effect certain differences in procedure or equipment will have on the result. Our previous attempt at looking at non-reading eye-movements in developmental dyslexics (Stanley, 1978) produced essentially the same results as another research group (Adler-Grin...

Previous research suggests that slower responding by mentally retarded individuals reflects impairments in those executive cognitive processes mediating rapid information-processing. We suggest that one approach to the clarification of the nature and extent of such impairments and, specifically, the involvement of structural and control process par...

Teachers were asked to select control children of comparable general ability to dyslexic children in their classes and differences between these two groups were examined. Manual Expression from the Illinois Test of Psycholinguistic Ability, Picture Completion, and Block Design from the WISC-R did not differ across groups. Picture Arrangement and Ob...

The properties of the detecting mechanism involved in the resolution of temporal discontinuities of visually presented stimuli have been investigated in two experiments. In Experiment 1, observers made judgments of discontinuity when superimposed presentations of sine-wave gratings of 1, 3, 6, and 10 cycles/deg were presented for either a 20- or a...

Lovegrove, Heddle, and Slaghuis (1980) have reported that disabled readers have significantly different temporal separation thresholds than normal for successive presentations of a sinewave grating. In the present study separation thresholds were obtained at high and low spatial frequencies, at two levels of contrast and two stimulus durations from...

A model of the psychological refractory period (PRP) proposed by Surwillo and Titus (1976) is compared critically with that proposed by Welford (1952) noting the following points: Surwillo and Titus augment the single channel hypothesis of Welford's model with other assumptions that are unnecessary as Welford's model fits their data (and the great...

Recent reports have shown neurodegenerative disorders to be associated with abnormal expansions of a CAG trinucleotide repeat allele at various autosomal loci. While normal chromosomes have 14 to 44 repeats, disease chromosomes may have 60 to 84 repeats. The number of CAG repeats on mutant chromosomes correlates with increasing severity of disease...