Exceptions to Hick's law: explorations with a response duration measure

Five experiments used a new response-duration measure in explorations of the conditions necessary for confirmation of Hick's law. Hick's law states that reaction time increases logarithmically with number of choices. Exceptions to the law, venerable as it is, have been reported. They have always included the following conditions: a verbal response; a familiar stimulus with a single dominant name; and a large number of practice trials. These conditions have carried a heavy explanatory burden in accounting for the anamolous results. The present studies use none of these conditions and yet manage to replicate the anamolous result of a very shallow slope across set size, a slope less than one-tenth the usual value. This was accomplished by using a novel task in which the initial component of the response is the same for all stimuli (depression of a single response key) but the termination of the response is different (different durations for each stimulus). Using this task, a slope in the neighborhood of 15 ms per bit of stimulus uncertainty is found, as compared with the usual value of about 150 ms. A number of possible explanations are examined. Among the most important are the possibilities that response overlap is the critical factor (i.e., duration errors overlap); possible stimuli are simply ignored when more than one is involved; and the duration decision is made after the reaction-time interval rather than during it. All three possibilities, as well as some others, are found to be inconsistent with the various experimental outcomes. Instead, a new theory of choice reaction time is presented, which emphasizes the nature of the S-R code that is assumed to represent various reaction-time tasks. This theory leads to a new "law" that is put forward as a replacement for Hick's law. It is RT = a + b(1 - N-1).     

Fitts' reciprocal tapping task, a measure of motor capacity?

Employing Fitts' reciprocal tapping task, the capacity of the motor system in bits processed/second was assessed across different ages. In Exp. I a comparison was made among Grades 1, 5, 9, and university females. Motor capacity and average movement time/tap were significantly lower for Grade 1 girls than the other three grades. In addition, within-subject variability and percentage error rate decreased with increasing grade level. These findings were discussed in comparison to other studies looking at motor capacity changes across ages. Exp. II was designed to study the changes in motor capacity throughout 25 days of practice by two 5-yr.-old children. Two different methods were used to calculate motor capacity. One method (Kay, 1962) which assessed motor capacity separately for each tapping condition led to the conclusion that capacity increased with practice. A second method (Fitts & Peterson, 1964) treating all tapping conditions together in a regression equation and measuring capacity as the reciprocal of the slope (1/b) showed capacity to decrease with practice for one subject and oscillate with practice for the other subject. The general conclusion drawn from the two experiments was that motor capacity, as assessed by Fitts' tapping task, is not an extremely useful measure. Consideration of movement time is usually just as informative.     

Patterns of adaptation in asthma and psoriasis

Patterns of adaptation to a conflict situation were explored by means of the repeated confrontation with the Stroop task (Serial Color-Word Test) in two clinical groups: bronchial asthma (n=40) and psoriasis (n=28). The respective psychosomatic component of each of these syndromes was expected to correspond to peculiar patterns of adaptation. Differences between asthma and psoriasis patients were statistically significant. Asthma was characterized by patterns with high values of nonlinear change, both within each subtest (Primary Types) and across the five subtests (Secondary Types). Psoriatic patients were classified most often as having the C(V) type (high linear increase of nonlinear changes across the subtests) and showed some more ITA+ types, i.e., within the first subtest, longer reading time at the beginning, followed by uniformly faster times.     

Association of race and color with mean IQ across nations

This study investigated the correlation of both race and skin color in the distribution of mean IQ for 129 countries with primarily indigenous populations. Skin color correlated most highly with mean IQ across the Caucasoid countries (r = -.86), somewhat less across the Mongoloid countries (r = -.66), and nonsignificantly across the Negroid countries (r = .06). When the Negroid and Caucasoid countries were combined, both race and skin color yielded high correlations with IQ (r = .87, -.95, respectively). When the Negroid and Mongoloid countries were combined, both race and skin color yielded high correlations with IQ (r = .91, -.91, respectively). When Caucasoid and Mongoloid countries were combined, skin color yielded a high correlation, but race did not correlate significantly with IQ. The greater importance of Negroid race was regarded as congruent with the 1998 generalization of Jensen that the genetic distance between Mongoloids and Caucasoid is less than the genetic distance of these two groups from Negroid.     

Response Style Differences in the Inattentive and Combined Subtypes of Attention-Deficit/Hyperactivity Disorder

This study examined potential differences between the inattentive and combined ADHD subtypes using laboratory tasks assessing behavioral inhibitory processes. Seventy-five children completed two tasks of behavioral inhibition believed to isolate different processes: the cued reaction time task (CRT), a basic inhibition task, and the go/no-go task (GNG), a complex inhibition task that incorporates motivational contingencies. Three groups of participants were identified, including ADHD/Inattentive (n = 17), ADHD/Combined (n = 37), and comparison (n = 21). Results indicated that rather than showing behavioral inhibition deficits, the ADHD/I children appeared overly inhibited, as evidenced by slower reaction times across the two tasks and significantly higher errors of omission in the GNG task. Additionally, the ADHD/I children did not demonstrate cue dependency effects on the CRT task, suggesting that they were failing to incorporate relevant information before making a response. The sluggish and inhibited performance of the ADHD/I group challenges the idea that it is a subtype of ADHD.     

Beyond visual fixations and gaze behaviour. Using pupillometry to examine the mechanisms in the planning and motor performance of a golf putt

The present study assessed the potential value of using pupillometry to explore skill level differences in the allocation of attention during planning and performance of a golf putt across three putting conditions of varying complexity. Although numerous studies have reported on skill level differences in performers' visual search behaviours, performance accuracy and quiet eye duration (QE) across a range of performance settings, few have provided an objective measure of the allocation of attention during task performance. Fourteen participants were assigned to two groups [low handicap (LHG) and high handicap (HHG)] completing ten putts in three conditions; right to left (RL), left to right (LR) and straight (ST) from 1.75 m while wearing a mobile eye tracker. Skill based differences in the allocation of attention during green exploration and skill execution were observed. Pupil constriction observed for both groups during the QE period provides evidence of increased workload directly related to the increased motor task precision required in the physical performance of the putt. LHG had significantly more fixations of longer duration than their HHG counterparts. Distinct differences were also evident between skill levels in relation to number of fixations, fixation duration and QE duration on each putting condition. The significantly longer QE duration and larger pupil constrictions exhibited by skilled performers offer evidence of a distinctive concentration of cognitive activity characterised by highly automated processes.     

Emergence of Information-Retrieval Strategies in Numerical Cognition: A Developmental Study

A series of simple addition problems was presented in a reaction time, true-false verification task to subjects in Grades 2 through 4 and in college. This information-processing paradigm was used to measure the solution strategies used for problems that sometimes are solved too rapidly and accurately to allow for meaningful error analysis. A series of structural models representing different processing sequences was tested against reaction times for solution to different two-term addition problems. Young children and adults alike used a memory access process to solve highly overlearned addition problems such as 1 + 1 = 2, but solution strategies of more difficult problems differed by age. Younger children adopted a slow, effortful, implicit counting strategy, with efficiency developing in the middle elementary school years; adults performed in a manner consistent with at least some models of memory retrieval found in the literature. Children were classified into two groups, independently of grade, based on slope values from a regression equation computed on individual subject data. The two groups comprised what appeared to be "fast" and "slow" processors, who differed in terms of speed of processing as well as strategy used. Our findings are discussed in terms of models of semantic memory and the development of automatic information-processing skills.     

Reaction time to threat stimuli in panic disorder and social phobia

Two studies assessed response time among clinically anxious subjects and normal controls when presented with threat, positive and neutral stimuli under perceptual (lexical decision) and semantic (category decision) task conditions. In Study 1, panic disorder subjects' (n = 14) performance was compared to that of matched normal controls (n = 14) while in Study 2 social phobic subjects (n = 24) were compared to matched normal controls (n = 24). Relative to matched normal controls, panic disorder subjects but not social phobics tended to show greater slowing in performance on the more cognitively complex (category) task. A second finding, consistent across both studies was that, compared to the normal control groups, both panic and social phobic groups showed significantly slowed responses to threat words in both the perceptual and semantic tasks. Such findings are directly counter to the predictions of a mood congruence hypothesis. This apparent contradiction is resolved by a review of the literature which indicates that mood-related facilitation effects are obtained only in tasks which tap awareness of threat information rather than speed of response. It is suggested that while anxiety may produce enhanced awareness of threat, it may inhibit responsiveness to it. The results of these studies are seen as consistent with ethological theories of inhibited motoric responses under certain threat conditions. Furthermore, the findings suggest that caution is indicated in interpreting slowed reaction time to threat stimuli in tasks such as the Stroop color naming task as purely the result of attentional processes.     

Health-Related Decision-Making in HIV Disease

Individuals living with HIV show moderate decision-making deficits, though no prior studies have evaluated the ability to make optimal health-related decisions across the HIV healthcare continuum. Forty-three HIV+ individuals with HIV-associated neurocognitive disorders (HAND+), 50 HIV+ individuals without HAND (HAND?), and 42 HIV? participants were administered two measures of health-related decision-making as part of a comprehensive neuropsychological battery: (1) The Decisional Conflict Scale (DCS), and (2) The Modified UCSD Brief Assessment for Capacity to Consent (UBACC-T). Multiple regression analyses revealed that HAND was an independent predictor of both the DCS and the UBACC-T, such that the HAND+ sample evidenced significantly poorer scores relative to comparison groups. Within the HIV+ sample, poorer health-related decision-making was associated with worse performance on tests of episodic memory, risky decision-making, and health literacy. Findings indicate that individuals with HAND evidence moderate deficits in effectively comprehending and evaluating various health-related choices.     

Time-varied noise effects on color-word test performance

The effects of continuous and time-varied 85 dBA broadband noise on the performance of a Stroop-type color-word test and a related word-reading task were investigated. 10 subjects served in one of three groups receiving either continuous, periodic, or aperiodic noise. All subjects performed in both low noise (65 dBA) and high noise (85 dBA) conditions on 80 trials of both word reading and color naming. Median reaction times in the word-reading task were unaffected by either noise intensity or the time-varied aspects of the noise. However, median reaction times in the color-naming task were significantly elevated in the 85-dBA noise condition. Also, reaction times in the high aperiodic noise condition were significantly elevated relative to the continuous and periodic noise conditions. Results are discussed within the framework of arousal, filter, and information theories.     

Effect of intermittent exercise on multiple-choice reaction times of soccer players

The influence of intermittent exercise on a choice-response time task was investigated. Two groups of 8 male soccer players (M age = 20.9, SD = 2.0) participated. They spent 4.4 (SD = 1.3) weekly hours on soccer training and had been playing soccer for 13 (SD = 3.3) years. Multiple-choice reaction speed and response accuracy were measured four times. Between measurements, one group performed 8-min. blocks of intermittent exercise on a bicycle ergometer and one group rested. Analysis showed that reaction speed and response accuracy were not significantly different between the two groups. Furthermore, there were significant faster reaction times and a larger number of correct reactions through Block 2 in both the exercise and control group (p < .05), probably a result of learning processes and familiarization with the task procedures. Further research towards the specific influence of mode of exercise, intensity, work-rest ratio and duration of intermittent exercise, and the sensitivity of reaction time tasks will be necessary to clarify the relationship between intermittent exercise and cognitive performance.     

Reaction Time Inconsistency in a Spatial Stroop Task: Age-Related Differences Through Childhood and Adulthood

ABSTRACT

Age-related differences in inconsistency of reaction time (RT) across the life span were examined on a task with differing levels of demand on executive control. A total of 546 participants, aged 5 to 76 years, completed a spatial Stroop task that permitted observations under three conditions (congruent, incongruent, and neutral) according to the correspondence between the required response (based on stimulus direction) and stimulus location. An interference effect was observed across all ages. Analyses of neutral condition data replicated previous research demonstrating RT inconsistency follows a U-shaped developmental curve across the life span. The relationship between age and inconsistency, however, depended on condition: inconsistency in the congruent condition was higher than inconsistency in both the neutral and incongruent conditions across middle-aged groups. Reaction time inconsistency may reflect processing efficiency that is maximal in young adulthood and may also be sensitive to fluctuations in performance that reflect momentarily highly efficient responding.     

Reaction time inconsistency in a spatial stroop task: age-related differences through childhood and adulthood

Age-related differences in inconsistency of reaction time (RT) across the life span were examined on a task with differing levels of demand on executive control. A total of 546 participants, aged 5 to 76 years, completed a spatial Stroop task that permitted observations under three conditions (congruent, incongruent, and neutral) according to the correspondence between the required response (based on stimulus direction) and stimulus location. An interference effect was observed across all ages. Analyses of neutral condition data replicated previous research demonstrating RT inconsistency follows a U-shaped developmental curve across the life span. The relationship between age and inconsistency, however, depended on condition: inconsistency in the congruent condition was higher than inconsistency in both the neutral and incongruent conditions across middle-aged groups. Reaction time inconsistency may reflect processing efficiency that is maximal in young adulthood and may also be sensitive to fluctuations in performance that reflect momentarily highly efficient responding.     

The effects of different exercise types on visuospatial attention in the elderly

While the capability of visuospatial attention decreases with advanced aging, exercise is an effective primary prevention strategy to ward off the progression of such cognitive declines among the elderly. However, no studies have yet been conducted on the relationship between exercise type and visuospatial attention in the elderly. This study was thus carried out to explore the effects of open- and closed-skill exercise modes on visuospatial attention in the elderly using behavioral and cognitive electrophysiological measurements. Sixty elderly participants were divided into open-skill (n = 20), closed-skill (n = 20), or control (n = 20) groups according to their exercise-participation experience in the previous 24 months, and performed a visuospatial attention task with concomitant electrophysiological recording. The results showed that the two exercise groups (i.e., open- and closed-skill) exhibited shorter reaction times (RTs) and larger P3 amplitudes across conditions compared with the control group. Although the open- and closed-skill groups only showed approaching between-group significance on the RTs in the invalid condition and on the P3 amplitudes across conditions, only the open-skill group showed better inhibitory control of attention relative to the control group. These findings reveal the presence of neurocognitive effects on the visuospatial attention task in the two exercise groups, with significantly better performances in the open-skill group, demonstrating that regularly participating in such an exercise mode, as compared to the closed-skill one, could have more beneficial effects on visuospatial attention.     

Central processing uncertainty as a determinant of choice reaction time

It was demonstrated that central processing uncertainty (Hc) can be derived to provide a single valued statement of the information hypothesis RT=a+b (Hc) across test stimulus sets and across several levels of test stimulus probability in an information reduction task. The derivation procedure assumes successive tests of stimulus hypotheses with Bayesian revision of stimulus probabilities after failure of an initial test. It was shown that the procedure can be generalized to data from single test stimuli in an information conservation task. Stimulus and response repetition effects were estimated for the information reduction task data.     

Distinct neural correlates for two types of inhibition in bilinguals: response inhibition versus interference suppression

To examine the effects of bilingualism on cognitive control, we studied monolingual and bilingual young adults performing a flanker task with functional MRI. The trial types of primary interest for this report were incongruent and no-go trials, representing interference suppression and response inhibition, respectively. Response times were similar between groups. Brain data were analyzed using partial least squares (PLS) to identify brain regions where activity covaried across conditions. Monolinguals and bilinguals activated different sets of brain regions for congruent and incongruent trials, but showed activation in the same regions for no-go trials. During the incongruent trials, monolinguals activated the left temporal pole and left superior parietal regions. In contrast, an extensive network including bilateral frontal, temporal and subcortical regions was active in bilinguals during the incongruent trials and in both groups for the no-go trials. Correlations between brain activity and reaction time difference relative to neutral trials revealed that monolinguals and bilinguals showed increased activation in different brain regions to achieve less interference from incongruent flankers. Results indicate that bilingualism selectively affects neural correlates for suppressing interference, but not response inhibition. Moreover, the neural correlates associated with more efficient suppression of interference were different in bilinguals than in monolinguals, suggesting a bilingual-specific network for cognitive control.     

Cross-modal correlation of dichotic and tachistoscopic language laterality tasks: the importance of familial sinistrality

Previous studies have found little if any correlation between dichotic and tachistoscopic language laterality task performance asymmetries. Problems with these studies have been that quite dissimilar auditory and visual tasks have often been used, and the reliability of the asymmetry measures has generally been unknown or, when known, relatively poor. We assessed the cross-modal correlation for two tasks, the Bilateral Object Naming Latency Task (BONLT) and the Dichotic Object Naming Latency Task (DONLT). These tasks are highly similar and have demonstrated high reliabilities. A significant, though rather small, cross-modal correlation was found (r = +.28). When cross-modal correlations were computed for FS- and FS+ subjects separately, no correlation was found for FS+ subjects (r = +.02), but the correlation for FS- subjects was highly significant (r = +.54, p less than .004). This led us to reexamine some previously collected data (P.L. Van Eys and W. F. McKeever, 1988, Brain and Cognition, 4, 413-429) which had administered two highly reliable language laterality tasks (the BONLT and the Dichotic Consonant Vowel Task), but had not assessed cross-modal correlation. A significant cross-modal correlation was found for FS- but not for FS+ subjects. The results are consistent with the hypothesis of H. Hecaen, M. De Agnostini, and A. Monzon-Montes (1981, Brain and Language, 12, 261-284) which suggests that one effect of FS+ is to induce a greater heterogeneity of localizations of different language processes.     

Reversed memory coding and symbol reversal in children

The present study examined an hypothesized mirror-reversed memory-coding phenomenon whereby aligned and mirror-reversed memory records in opposite cerebral hemispheres are confused. Two groups of 7-yr.-old boys were chosen on the basis of tendency to confuse mirror and aligned written symbols. The experimental task required discrimination as same or different of letter pairs which were either same or different and either aligned or mirror-reversed. The pairs were simultaneously presented to right, left, or both cerebral hemispheres. The reversing group had slower reaction times than the normal group in all conditions. Evidence was insufficient to conclude that mirror-same bilateral presentation facilitated responses of either group over aligned-same or peripheral conditions. This result would have been necessary to indicate the presence of a mirror-reversed code across the hemispheres. Research utilizing delayed as well as simultaneous presentation of stimuli to children of various ages would clarify this ambiguity. Bilateral processing across conditions proved easier for both groups, indicating adequate hemispheric integration on a visual-perceptual task even in children who tended to confuse mirror images.     

Baby arithmetic: one object plus one tone

Recent studies using a violation-of-expectation task suggest that preverbal infants are capable of recognizing basic arithmetical operations involving visual objects. There is still debate, however, over whether their performance is based on any expectation of the arithmetical operations, or on a general perceptual tendency to prefer visually familiar and complex displays. Here we provide new evidence that 5-month-old infants recognize basic arithmetic operations across sensory modalities. Using a violation-of-expectation task that eliminated the possibility of the familiarity and complexity preference, 5-month-old infants were presented alternatively with two types of arithmetical events: the expected, correct outcomes of operations (1 object+1 tone=2 objects and 1 object+2 tones=3 objects) and the unexpected, incorrect ones (1 object+2 tones=2 objects and 1 object+1 tone=3 objects). Results showed that subjects looked significantly longer at the unexpected events than at the expected events, suggesting that infants are able to recognize basic arithmetic operations across sensory modalities.     

Personality stability in late adulthood: a behavioral genetic analysis

A sample of 833 twins from the Minnesota Twin Study of Adult Development and Aging completed the Multidimensional Personality Questionnaire (MPQ; Tellegen, 1982) twice, averaging 59.4 (sd=9.7) years of age at first and 64.4 (sd=10.2) years of age at second testing (average retest interval 5.0 years, sd=2.36, range 1.0-10.4 years). Both means and standard deviations of scale scores were extremely stable from first to second testing. In addition, sample participants tended to retain their rank order on the scales (average r=.76 across scales). Bivariate biometric analyses showed that the genetic influences on most of the scale scores were almost perfectly correlated across the two waves (range .95 to 1.00). The nonshared environmental influences were also highly correlated across the two waves (range .53 to .73). Models specifying identical variance components at the two time points and fixing the genetic correlation to 1.00 provided improved fit. The results suggest that the high stability of personality in later adulthood has a strong genetic foundation, supplemented by stability of environmental effects.