Individual Differences In Task Performance Research Articles

Hitting the reset button: An ERP investigation of memory for temporal context

This study explored how temporal context influences recognition. In an ERP experiment, subjects were asked to judge whether pictures, presented one at a time, had been seen since the previous appearance of a special reset screen. The reset screen separated sequences of successively presented stimuli and signaled a change in temporal context. A “new-repeat” picture was one that had been seen before but was to be called “new” because it had not appeared since the previous reset screen. New-repeat pictures elicited a more negative FN400 component than did “old” pictures even though both had seen before during the experiment. This suggests that familiarity, as indexed by the FN400, is sensitive to temporal context. An earlier frontopolar old/new effect distinguished pictures that were seen for the first time in the experiment from all other pictures. The late positive component (LPC), which is typically greater for old stimuli, was smaller for new-repeat pictures than for pictures seen for the first time in the experiment. Finally, individual differences in task performance were predicted by the differences in amplitude of P3b that was evoked by the onset of the reset screen.

Task-positive Functional Connectivity of the Default Mode Network Transcends Task Domain.

The default mode network (DMN) was first recognized as a set of brain regions demonstrating consistently greater activity during rest than during a multitude of tasks. Originally, this network was believed to interfere with goal-directed behavior based on its decreased activity during many such tasks. More recently, however, the role of the DMN during goal-directed behavior was established for internally oriented tasks, in which the DMN demonstrated increased activity. However, the well-documented hub position and information-bridging potential of midline DMN regions indicate that there is more to uncover regarding its functional contributions to goal-directed tasks, which may be based on its functional interactions rather than its level of activation. An investigation of task-related changes in DMN functional connectivity during a series of both internal and external tasks would provide the requisite investigation for examining the role of the DMN during goal-directed task performance. In this study, 20 participants underwent fMRI while performing six tasks spanning diverse internal and external domains in addition to a resting-state scan. We hypothesized that the DMN would demonstrate "task-positive" (i.e., positively contributing to task performance) changes in functional connectivity relative to rest regardless of the direction of task-related changes in activity. Indeed, our results demonstrate significant increases in DMN connectivity with task-promoting regions (e.g., anterior insula, inferior frontal gyrus, middle frontal gyrus) across all six tasks. Furthermore, canonical correlation analyses indicated that the observed task-related connectivity changes were significantly associated with individual differences in task performance. Our results indicate that the DMN may not only support a "default" mode but may play a greater role in both internal and external tasks through flexible coupling with task-relevant brain regions.

Functional networks and structural connectivity of visuospatial and visuoperceptual working memory.

Neural correlates of working memory (WM) in healthy subjects have been extensively investigated using functional MRI (fMRI). However it still remains unclear how cortical areas forming part of functional WM networks are also connected by white matter fiber bundles, and whether DTI measures, used as indices of microstructural properties and directionality of these connections, can predict individual differences in task performance. fMRI data were obtained from 23 healthy young subjects while performing one visuospatial (square location) and one visuoperceptual (face identification) 2-back task. Diffusion tensor imaging (DTI) data were also acquired. We used independent component analysis (ICA) of fMRI data to identify the main functional networks involved in WM tasks. Voxel-wise DTI analyses were performed to find correlations between structural white matter and task performance measures, and probabilistic tracking of DTI data was used to identify the white matter bundles connecting the nodes of the functional networks. We found that functional recruitment of the fusiform and the inferior frontal cortex was specific for the visuoperceptual working memory task, while there was a high overlap in brain activity maps in parietal and middle frontal areas for both tasks. Axial diffusivity and fractional anisotropy, of the tracts connecting the fusiform with the inferior frontal areas correlated with processing speed in the visuoperceptual working memory task. Although our findings need to be considered as exploratory, we conclude that both tasks share a highly-overlapping pattern of activity in areas of frontal and parietal lobes with the only differences in activation between tasks located in the fusiform and inferior frontal regions for the visuoperceptual task. Moreover, we have found that the DTI measures are predictive of the processing speed.

Age Differences in the Processing of Context Information

The dual mechanisms of control theory (DMC; Braver & Barch, 2002 ) assumes that age-related changes in the temporal structure of context processing underlie age differences in numerous cognitive control tasks. Younger adults usually exhibit a proactive control mode, characterized by cue-related context updating, while older adults show a reactive control mode, updating information when interference is detected. This study aimed at determining whether age differences in electrophysiological correlates of context updating in a pro-and reactive manner are independent of individual differences in task performance. To this end, younger and older adults were split into four groups according to their updating efficiency in behavioral data. Nineteen younger and 18 older adults completed a modified AX-Continuous-Performance Task ( Lenartowicz, Escobedo-Quiroz, & Cohen, 2010 ) in which correct responses to probes were either dependent (c-dep) or independent (c-indep) on a preceding contextual cue. Analysis of the behavioral data showed no differences in context updating when performance was matched, that is, between low performing younger and high performing older adults. However, low performing younger adults showed larger cue-locked parietal P3b amplitudes on c-dep than c-indep trials, indicating c-dep trials to require context updating to a larger extent, while high performing older adults exhibited a specific control strategy and continuously updated context information, as reflected in comparable P3b amplitudes on c-dep and c-indep trials. The persistent age effect in the P3b when controlling for performance differences suggests context updating to be fundamental to cognitive aging. High performing in contrast to low performing older adults also showed a larger negative N450 to ambiguous probes on c-dep trials associated with conflict detection. According to the DMC, this finding suggests late conflict detection at the time interference is detected, indicative of a reactive control style particular in high performing elderly.

Further response to Hampshire et al.

We explain that Hampshire, Parkin, Highfield, and Owen (2014b) have not demonstrated any orthogonality of brain network capacities and that a model of mental ability structure must make testable predictions about individual differences in task performance. Evidence thus far indicates that g-based models account for intercorrelations among mental ability tasks better than do task mixing or blended variable models.

Unconscious errors enhance prefrontal-occipital oscillatory synchrony

The medial prefrontal cortex (MFC) is critical for our ability to learn from previous mistakes. Here we provide evidence that neurophysiological oscillatory long-range synchrony is a mechanism of post-error adaptation that occurs even without conscious awareness of the error. During a visually signaled Go/No-Go task in which half of the No-Go cues were masked and thus not consciously perceived, response errors enhanced tonic (i.e., over 1–2 s) oscillatory synchrony between MFC and occipital cortex (OCC) leading up to and during the subsequent trial. Spectral Granger causality analyses demonstrated that MFC → OCC directional synchrony was enhanced during trials following both conscious and unconscious errors, whereas transient stimulus-induced occipital → MFC directional synchrony was independent of errors in the previous trial. Further, the strength of pre-trial MFC-occipital synchrony predicted individual differences in task performance. Together, these findings suggest that synchronous neurophysiological oscillations are a plausible mechanism of MFC-driven cognitive control that is independent of conscious awareness.

G and the measurement of Multiple Intelligences: A response to Gardner

Gardner [Gardner, H. (2006-this issue). On failing to grasp the core of MI theory: A response to Visser et al. Intelligence] criticized some aspects of our empirical examination [Visser, B. A., Ashton, M. C., & Vernon, P. A. (2006-this issue). Beyond g: Putting multiple intelligences theory to the test. Intelligence] of his “Theory of Multiple Intelligences”. Specifically, Gardner questioned the construct validity of g, and suggested that the measures we used to test his theory were contaminated with verbal and logical demands. In this reply, we explain that the construct validity of g is well established, pointing out (a) that g is expressed in a wide variety of tasks (not all of which are “school-like” tasks), (b) that g predicts many important criterion variables (not only academic achievement), and (c) that g has a well-established biological basis. With regard to the measures used in our study, we point out that the verbal content of those tasks is unlikely to contribute to individual differences in task performance, and that the logical content of those tasks is consistent with Gardner's description of his intelligence domains.

Flexible cognitive control: Effects of individual differences and brief practice on a complex cognitive task

Brain activations underlying cognitive processes are subject to modulation as a result of increasing cognitive demands, individual differences, and practice. The present study investigated these modulatory effects in a cognitive control task which required inhibition of prepotent responses based on the contents of working memory (WM) and which enabled a novel dissociation of item-specific and task-skill effects resulting from brief practice. Distinct responses in areas underlying WM and inhibitory control in the absence of behavioral changes reflected different effects of item repetition and general task practice on tonic working memory and phasic inhibitory processes. Item repetition was associated with decreases in both unique and common areas subserving WM and inhibitory control. In contrast, general task practice was reflected in decreases in the level of tonic WM activity required to maintain a consistently high level of task performance but increased activity in a number of core inhibitory regions including dorsolateral and inferior PFC and inferior parietal cortex. Furthermore, both practice and individual differences in task performance were associated with the ability to modulate and maintain activity in frontostriatal areas mediating attentional control, suggesting that the areas that differ between individuals can be modulated by practice within an individual. These results raise the possibility that a fundamental human ability, reflexive cognitive control, is amenable to practice.

A correlational analysis of skill specificity: Learning, abilities, and individual differences.

Skill specificity, the notion that task performance is based on unique underlying information-processing components at skilled levels of performance, is examined from the perspective of the ability determinants of individual differences in task performance during skill acquisition.

Accommodating individual differences in searching a hierarchical file system

Individual differences among users of a hierarchical file system were investigated. The results of a previous experiment revealed that subjects with low spatial ability were getting lost in the hierarchical file structure. Based on the concept of visual momentum, two changes to the old interface were proposed in an attempt to accommodate the individual differences in task performance. The changes consisted of a partial map of the hierarchy and an analogue indicator of current file position. This experiment compared the performance of users with high and low spatial abilities on the old verbal interface and the new graphical interface. The graphical interface resulted in changes in command usage that were consistent with the predictions of the visual momentum analysis. Although these changes in strategy resulted in a performance advantage for the graphical interface, the relative performance difference between high and low spatial groups remained constant across interfaces. However, the new interface did result in a decrease in the within-group variability in performance.

Influence of Peripheral Visual Distraction on Perceptual Motor Performance

Twelve students of the University of Waterloo served as Ss in a psychomotor study of the influence of extraneous stimuli in the peripheral visual field. Individual differences in task performance also were examined in relation to the personality characteristics of extraversion and neuroticism. The presentation of irrelevant stimuli beyond the center of attention or visual focus was found to retard response to irregular signals for action but accuracy in responding to predictable signals was unaltered. Repeated testing under different interpolated rest schedules did not alter psychomotor performance. The stability of performance indicated that learning on the task was minimal. Since many drug and other treatment effects are best assessed by repeated testing of the same individual, it was suggested that this task could be a valuable device in such research, to evaluate treatment effects independent of learning. The evidence relating individual differences in performance to extraversion and to neuroticism was not conclusive, and some further research was suggested to clarify the questions raised by this study.

Individual differences in task performance under conditions of cognitive interference.

Individual differences in task performance under conditions of cognitive interference.