Impulsivity and Paced Tapping

The purpose of this study was to test the hypothesis that impulsivity is positively related to both the intraindividual variability and the rate of performance of a paced tapping task. Selected experimental conditions which have been demonstrated to influence paced tapping were included in the experimental design of the tapping task. The independent variables in the tapping task were: feedback vs. no feedback; tempo; concurrent cognitive task (counting) vs. no concurrent cognitive task. Three measures of tapping performance were computed: absolute or total error of tapping, tapping rate, and the intraindividual variability of tapping. The results confirm the hypothesis that impulsivity is positively related to rate of paced tapping, although the degree of relationship varied under different experimental conditions within the paced tapping task. Intraindividual variability of tapping was not significantly related to impulsivity, but the results were suggestive of a positive relationship.     

Intraindividual variability may not always indicate vulnerability in elders' cognitive performance

This study examined consistency of performance, or intraindividual variability, in older adults' performance on 3 measures of cognitive functioning: inductive reasoning, memory, and perceptual speed. Theoretical speculation has suggested that such intraindividual variability may signal underlying vulnerability or neurologic compromise. Thirty-six participants aged 60 and older completed self-administered cognitive assessments twice a day for 60 consecutive days. Intraindividual variability was not strongly correlated among the 3 cognitive measures, but, over the course of the study, intraindividual variability was strongly intercorrelated within a task. Higher average performance on a measure was associated with greater performance variability, and follow-up analyses revealed that a higher level of intraindividual variability is positively associated with the magnitude of a person's practice-related gain on a particular measure. The authors argue that both adaptive (practice-related) and maladaptive (inconsistency-related) intraindividual variability may exist within the same individuals over time.     

Rate and variability of finger tapping as measures of lateralized concurrent task effects

Using a sample of 48 normal right-handed adults, we assessed the effects of oral reading on concurrent unimanual finger tapping under all combinations of instructional set (speeded vs. consistent tapping), tapping movement (repetitive vs. alternating), task emphasis (reading emphasized vs. tapping emphasized), and tapping hand. Change in tapping rate and variability was measured relative to the corresponding single task control condition. Reading decreased the rate of speeded finger tapping but increased the rate of consistent tapping. In both instances, the right hand was affected more than the left hand. Asymmetries were comparable for repetitive and alternating tapping. When measured in terms of variability, however, effects were largely symmetric. The findings clarify the conditions under which lateralized concurrent task effects are most likely to occur and show that such effects are not statistical artifacts. It appears that subjects attempt to coordinate the timing of concurrent activities and that speech timing is more strongly linked to right-hand control than to left-hand control in right-handers.     

Change in intraindividual variability over time as a key metric for defining performance-based cognitive fatigability

Cognitive fatigability is conventionally quantified as the increase over time in either mean reaction time (RT) or error rate from two or more time periods during sustained performance of a prolonged cognitive task. There is evidence indicating that these mean performance measures may not sufficiently reflect the response characteristics of cognitive fatigue. We hypothesized that changes in intraindividual variability over time would be a more sensitive and ecologically meaningful metric for investigations of fatigability of cognitive performance. To test the hypothesis fifteen young adults were recruited. Trait fatigue perceptions in various domains were assessed with the Multidimensional Fatigue Index (MFI). Behavioral data were then recorded during performance of a three-hour continuous cued Stroop task. Results showed that intraindividual variability, as quantified by the coefficient of variation of RT, increased linearly over the course of three hours and demonstrated a significantly greater effect size than mean RT or accuracy. Change in intraindividual RT variability over time was significantly correlated with relevant subscores of the MFI including reduced activity, reduced motivation and mental fatigue. While change in mean RT over time was also correlated with reduced motivation and mental fatigue, these correlations were significantly smaller than those associated with intraindividual RT variability. RT distribution analysis using an ex-Gaussian model further revealed that change in intraindividual variability over time reflects an increase in the exponential component of variance and may reflect attentional lapses or other breakdowns in cognitive control. These results suggest that intraindividual variability and its change over time provide important metrics for measuring cognitive fatigability and may prove useful for inferring the underlying neuronal mechanisms of both perceptions of fatigue and objective changes in performance.     

Lateralized interference in finger tapping: comparisons of rate and variability measures under speed and consistency tapping instructions

Forty right-handed college subjects tapped with and without a verbal task under two instructional conditions (tap as quickly as possible vs. tap as consistently as possible) and two levels of verbal production (silent vs. aloud). The tapping task consisted of the alternate tapping of two keys with the index finger of the left vs. right hands, while the verbal task was anagram solution. Three rate and four variability measures of tapping performance were evaluated in the identification of lateralized interference. The results indicate that reliable lateralized interference, more right-hand than left-hand tapping disruption, was observed only for variability measures under instructions to tap as consistently as possible. Furthermore, only one of these variability measures was sensitive to an increase in lateralized interference produced by verbal production. Because of the limited demonstration of verbal laterality effects with the two-key tapping procedure in this study, conclusions suggest that the simpler manual task of repetitive tapping of one key should be viewed as the method of choice in future dual-task studies.     

Performance and motivational deficits of helplessness: the role of motivational orientations

The present study examined the hypothesis that the effect of failure feedback in producing learned helplessness would depend on the motivational orientation of a child. Extrinsically motivated children were predicted to exhibit performance decrement following a failure experience, whereas the opposite was predicted for intrinsically motivated children. In addition, success feedback was predicted to enhance subsequent performance only for the intrinsic group. Following success, failure, or no feedback on an activity reflecting spatial skills (an incomplete picture task), subjects' performance on an activity tapping different skills (i.e., anagrams) provided by a second experimenter served as the primary measure of helplessness. Subjects' intrinsic motivation in performing the incomplete picture task, a similar task (embedded figures) and a dissimilar task (dots-to-dots) was also examined. The results supported the predictions on both performance and intrinsic motivation measures. The results are discussed in terms of implications for learned helplessness as well as cognitive evaluation theories.     

Task performance and electromyopotential as functions of task difficulty and EMG feedback

The dearth of empirical research in the application of biofeedback is discussed. Exp. 1 assessed relationships among biofeedback EMG training, EMG levels, cognitive task performance, and task difficulty. 72 subjects (male or female college students) were administered 1 trial on an iconic memory task with either EMG audio feedback, sham EMG audio feedback, or no feedback. Three levels of task difficulty were used. One 20-min. training session significantly lowered EMG responses, and task performance was inversely related to task difficulty. No relationship between EMG level and task performance was observed. Exp. 2 investigated the effect of increased EMG responses on cognitive task performance for one level of difficulty. One biofeedback training session did not significantly increase frontalis EMG, and there was no relationship between increased EMG and task performance.     

II Sensory feedback influences on keytapping motor tasks

Subjects were trained to tap a key continuously at a specific rate, and with a specific amount of pressure (regularity task). Performance of this task was studied under conditions of: (a) decreased auditory feedback (masking noise through earphones), (b) decreased visual feedback (tapping hand screened from view), (c) vibration (vibrators applied to forearm in order to “mask” proprioceptive feedback), (d) digital block of tapping finger, and (e) combination of all four conditions. Significant changes in rate and intensity of tapping resulted under conditions of decreased auditory feedback, vibration, and the combined condition.

In the second part of the study, the effects of different delayed sensory events on keytapping were examined. The five conditions of delayed sensory feedback were: (a) delayed auditory feedback, (b) delayed visual feedback, (c) delayed tactile feedback, (d) the first three delayed sensory events presented simultaneously, and (e) condition (d) repeated with digital block of the tapping finger.

The conditions of delayed sensory feedback did not markedly alter performance of the regularity task. The same conditions of delayed sensory feedback did, however, produce highly significant changes in the performance of a more complex pattern task. All of these delay conditions produced parallel changes in the pattern task, namely increased intensity and decreased rate of tapping. The fact that the pattern task is more disturbed by delayed sensory feedback than the regularity task suggests that temporal complexity of the task is one determinant of the degree to which it will be disturbed by a delay in sensory feedback.     

Age-related differences in concurrent-task performance of normal adults: evidence for a decline in processing resources.

A concurrent-task paradigm was used to investigate age-related differences in the attentional capacity of 92 right-handed adults. Young, middle-aged, and elderly Ss were compared as they performed speeded, unimanual finger tapping with and without concurrent silent reading, speaking, and maze completion. There were 2 levels of difficulty for each cognitive task. The decrement in tapping rate from the single- to dual-task condition increased linearly with age. Concurrent-task tapping was slowed more by difficult than by easy tasks, and difficult tasks had a disproportionately disruptive effect on the concurrent performance of elderly Ss. The heightened vulnerability of the elderly to concurrent-task effects cannot be attributed parsimoniously to either general slowing or diminution of a specific resource. Instead the results suggest a reduction in a general-purpose processing resource with increasing age.     

Field dependence-independence from a working memory perspective: a dual-task investigation of the Hidden Figures test

Field dependence-independence (FDI) is a construct intensively investigated within cognitive style research, but its cognitive underpinnings are not clearly specified. We propose that performance on FDI tasks primarily reflects the operations of the visuospatial and executive components of working memory. We tested this hypothesis in a dual-task experiment with a commonly used measure of FDI, the Hidden Figures Test. The results showed that performance on this test was impaired by concurrent performance of secondary tasks that primarily tap the visuospatial component (spatial tapping) and the executive component (2-back and random number generation), but was almost unaffected by other secondary tasks (simple tapping and articulatory suppression). Moreover, an analysis of secondary task performance ruled out the possibility of strategic trade-offs and revealed an intriguing dissociation for two different sets of "randomness" indices for the random number generation task. These results support the hypothesised mapping between FDI and working memory components and suggest that the dual-task paradigm can provide a useful way to bring underspecified constructs like FDI into closer alignment with theoretical ideas developed within cognitive psychology.     

Residual attentional capacity amongst young and elderly during dual and triple task walking

Walking is considered an automatic function which demands little attentional resources. Thus a residual attentional capacity is available for a concurrent task (dual task). Minor age-related deficits in postural control may minimize the residual attentional capacity, however this may not be detected by a simple examination of the individuals gait performance. This study investigated the use of challenging dual task combinations to detect age related changes in gait performance. Eleven community-dwelling elderly (mean age 76 years) and 13 young subjects (mean age 26 years) participated in the study. The participants walked along a figure-of-eight track at a self-selected speed. The effect of introducing a concurrent cognitive task and a concurrent functional motor task was evaluated. Stride-to-stride variability was measured by heel contacts and by trunk accelerometry. In response to the cognitive task the elderly increased their temporal stride-to-stride variability by 39% in the walking task and by 57% in the combined motor task. These increases were significantly larger than observed for the young. Equivalent decreases in trunk acceleration autocorrelation coefficients and gait speed were found. A combination of sufficiently challenging motor tasks and concurrent cognitive tasks can reveal signs of limited residual attentional capacity during walking amongst the elderly.     

Effects of age, task, and frequency on variability of finger tapping

The goal was to assess whether prior studies might have overestimated performance variability in older adults in dual task conditions by relying on primary motor tasks that are not constant with aging. 30 younger and 31 older adults performed a bimanual tapping task at four different frequencies in isolation or concurrently with a secondary task. Results showed that performance of younger and older adults was not significantly different in performing the tapping task at all frequencies and with either secondary task, as indicated by mean tapping performance and low number of errors in the secondary tasks. Both groups showed increased variability as tapping frequency increased and with the presence of a secondary task. Tapping concurrently while reading words increased tapping variability more than tapping concurrently while naming colours. Although older participants' performances were overall more variable, no interaction effects with age were found and at the highest frequencies of tapping, younger and older participants did not differ in performance.     

Impulsivity,intelligence, and academic performance: Testing the interaction hypothesis

Previous research suggests a moderator effect of intelligence on the relationship between impulsivity and academic achievement. However, the interaction hypothesis has not been adequately tested so far. The present study was aimed to analyze the interrelations between impulsivity, intelligence, and academic performance, with special interest in testing the interaction effect between impulsivity and intelligence in the prediction of performance. To that end, 174 university students, aged from 18 to 37 years, were tested. Analyses were carried out at the latent level in order to minimize measurement error and to increase statistical power. The main findings of the study show that: (a) impulsivity was negatively related to both academic performance and intelligence; (b) intelligence was positively related to academic performance; (c) impulsivity and intelligence contributed significantly and independently to predict and explain academic performance; and (d) there was a significant interaction effect between impulsivity and intelligence in predicting academic performance, such that impulsivity was more strongly associated with performance among the more intelligent students than among the less intelligent ones.     

The effect of feedback sign on task performance depends on self-concept discrepancies

Control theories claim that information about performance is often used by multiple goal systems. A proposition tested here was that performance information can create discrepancies in self-concept goals, directing cognitive resources away from the task goal system. To manipulate performance information, 160 undergraduates were given false positive or false negative normative feedback while working on a task that did or did not require substantial cognitive resources. Half of the participants were then given an opportunity to reaffirm their self-concepts following feedback, whereas half were not. Feedback sign positively related to performance only for those working on the cognitively intense task and not given a chance to reaffirm. Otherwise, feedback sign was negatively related to performance, albeit weakly.     

Dual task performance in children: generalized and lateralized effects of memory encoding upon the rate and variability of concurrent finger tapping

Interference between concurrent tasks was used to investigate the brain basis of capacity limitations apparent when children encode information. Seventy-three right-handed children in Grades 1-4 engaged in speeded unilateral finger tapping while encoding a variable number of faces or numbers for subsequent recognition testing. With both face and number encoding, tapping rate decreased as memory load increased. Encoding numbers was more disruptive than encoding faces. Both encoding tasks slowed right-hand tapping more than left-hand tapping, relative to control tapping performance, but had only a bilateral effect on the variability of tapping. Although overall interference was less than that observed with a comparison task (i.e., speaking), the asymmetry of interference was comparable. The results suggest that cerebral lateralization for memory encoding, as well as for speech, is constant across the age range of 6-10 years. Findings regarding developmental change in overall capacity, however, are task specific: interference from speaking but not from memory encoding decreases with increasing age.     

On the relationship between task performance and associated verbalizable knowledge

Three experiments explore the relationship between performance on a cognitive task and the explicit or reportable knowledge associated with that performance (assessed here by written post-task questionnaire). They examine how this relationship is affected by task experience, verbal instruction and concurrent verbalization. It is shown that practice significantly improves ability to control semi-complex computer-implemented systems but has no effect on the ability to answer related questions. In contrast, verbal instruction significantly improves ability to answer questions but has no effect on control performance. Verbal instruction combined with concurrent verbalization does lead to a significant improvement in control scores. Verbalization alone, however, has no effect on task performance or question answering.     

Asymmetry of Verbal-Manual Interference - Dissociation Between Rate and Variability in Left-Handers

In two experiments, 48 right-handed and 48 left-handed adults, respectively, performed speeded and consistent finger tapping with and without concurrent oral reading. Interference was measured in terms of change in tap-to-tap rate and variability. Experiment 1 confirmed a previous report that concurrent reading decreases the rate of speeded finger tapping and increases the rate of consistent tapping in right-handers, and that the right hand is affected more than the left. Experiment 2 showed that, for left-handers, concurrent reading decreases the rate of left-hand tapping more than right-hand tapping but increases the variability of the right hand more than the left. The double dissociation in left-handers between hand and dependent variable suggests that the speed and variability reflect different mechanisms of intertask interference. More generally, the findings illustrate the multidimensionality of motor performance and the risk of making inferences about neural organization on the basis of a single dependent measure.     

Self-induced versus reactive triggering of synchronous movements in a deafferented patient and control subjects

The present study investigates the contribution of tactile-kinesthetic information to the timing of movements. The relative timing of simultaneous tapping movements of finger and foot (hand-foot asynchrony) was examined in a simple reaction time task and in discrete self-initiated taps (Experiment 1), and in externally triggered synchronization tapping (Experiment 2). We compared the performance of a deafferented participant (IW) to the performance of two control groups of different ages. The pattern of results in control groups replicates previous findings: Whereas positive hand-foot asynchronies (hand precedes foot) are observed in a simultaneous reaction to an auditory stimulus, hand-foot asynchronies are negative with discrete self-initiated as well as auditorily paced sequences of synchronized finger and foot taps. In the first case, results are explained by a simultaneous triggering of motor commands. In contrast, self-initiated and auditorily paced movements are assumed to be controlled in terms of their afferent consequences, as provided by tactile-kinesthetic information. The performance of the deafferented participant differed from that of healthy participants in some aspects. As expected on the basis of unaffected motor functions, the participant was able to generate finger and foot movements in reaction to an external signal. In spite of the lack of movement-contingent sensory feedback, the deafferented participant showed comparable timing errors in self-initiated and regularly paced tapping as observed in control participants. However, in discrete self-initiated taps IW's hand-foot asynchronies were considerably larger than in control participants, while performance did not differ from that of controls in continuous movement generation. These findings are discussed in terms of an internal generation of the movement's sensory consequences (forward-modeling).     

Sequence initiation performance by stutterers under conditions of response competition

Male stutterers and nonstutterers were compared on their performance of a task that required tapping keys as rapidly and accurately as possible to reproduce different sequences of finger movements as soon as they had been demonstrated on a visual display panel. Testing using the right hand alone confirmed previous findings that stutterers are significantly slower than nonstutterers in initiating new movement sequences and make significantly more errors on initial sequences. Subjects were also tested on this sequence reproduction task while they performed concurrently a manual task with the left hand that required turning a knob in response to signal tones. The hypothesis underlying the study was that associated with stuttering is a dysfunction in the mechanisms regulating interhemispheric communication, and it was predicted that the concurrent task would interfere more with the sequence reproduction task performance of stutterers than with that of nonstutterers. A joint analysis of the speed and accuracy aspects of performance of the two tasks confirmed the prediction. Additional research required to clarify whether the effects are in fact due to the hypothesized interhemispheric mechanisms or to a generally greater susceptibility of stutterers to interference from any concurrent motor or cognitive activity is discussed.     

Performance variability is related to change in cognition: evidence from the Victoria Longitudinal Study

Performance variability across repeated task administrations may be an important indicator of age-related cognitive functioning. In the present investigation, the authors examined whether age differences and change in inconsistency were related to 6-year (3 occasion) cognitive change. Inconsistency scores were computed from 4 reaction time tasks performed by 446 older adults (54-89 years). Replicating previous cross-sectional results, greater inconsistency was observed for older participants even after controlling for differences in response speed. New longitudinal results demonstrated (a) associations between inconsistency at baseline measurement and 6-year change in cognitive performance; (b) longitudinal change in inconsistency; and (c) intraindividual covariation between 6-year change in inconsistency and 6-year change in level of cognitive function. These findings support the view that performance variability serves as a marker of cognitive aging.