Exploring Individual Differences as Predictors of Performance Change During Dual-N-Back Training.

In working memory training studies, individual trajectories are known to vary considerably between participants. A better understanding of how individual differences affect training outcomes is important because it might inform the development of more effective training interventions. This study explored how measures of working memory, intelligence, sustained attention, training motivation, mindset, psychological well-being, perceived stress, and sleep quality affect initial training performance and rate of change. A total of 217 upper secondary students completed 12 weeks of adaptive dual-n-back in a classroom setting. We analyzed their self-reported training data using latent growth curve modeling. We found that working memory and intelligence predicted both, initial training performance and rate of performance change. Sustained attention and sleep quality predicted initial performance, but not the rate of change. Furthermore, we observed that participants who completed the intervention scored significantly higher on measures of working memory and intelligence and reported lower levels of perceived stress and higher levels of sleep quality at baseline compared to dropouts. In general, our study supports the magnification account with higher ability individuals starting out at a higher performance level and showing a higher rate of performance change, and moreover, being more likely to adhere to the training protocol.

The relationship between methods of scoring the alternate uses task and the neural correlates of divergent thinking: Evidence from voxel-based morphometry.

Divergent thinking tests have been used extensively in neuroscientific studies of creativity. However, output from tests of divergent thinking can be scored in different ways, and those scores can influence assessments of divergent thinking performance and its relationship with brain activation. Here we sought to investigate the relationship between various methods of scoring the Alternate Uses Task (AUT)-a well-known test of divergent thinking-and regional grey matter volume (GMV) using voxel-based morphometry (VBM). We assessed AUT performance based on (a) traditional approaches that involve scoring participants' output on fluency, flexibility, originality, and elaboration, (b) a subjective approach that involves scoring output directly on "snapshot" creativity, and (c) the definitional approach that involves scoring output separately on novelty and usefulness-the two criteria deemed necessary and jointly sufficient to categorize an idea as creative. Correcting for age, sex, intracranial volume, verbal IQ and working memory capacity, we found negative correlations between regional GMV in the left inferior temporal gyrus (ITG) and novelty and usefulness scores, but no correlation involving other scoring approaches. As part of the brain's core semantic system, this region is involved in concept retrieval and integration. We discuss the implications of these findings for our understanding of the neural bases of divergent thinking, and how ITG could be related to the generation of novel and useful responses.

The Reflective Mind: Examining Individual Differences in Susceptibility to Base Rate Neglect with fMRI.

Performance on heuristics and bias tasks has been shown to be susceptible to bias. In turn, susceptibility to bias varies as a function of individual differences in cognitive abilities (e.g., intelligence) and thinking styles (e.g., propensity for reflection). Using a classic task (i.e., lawyer-engineer problem), we conducted two experiments to examine the differential contributions of cognitive abilities versus thinking styles to performance. The results of Experiment 1 demonstrated that the Cognitive Reflection Test (CRT)-a well-established measure of reflective thinking-predicted performance on conflict problems (where base rates and intuition point in opposite directions), whereas STM predicted performance on nonconflict problems. Experiment 2 conducted in the fMRI scanner replicated this behavioral dissociation and enabled us to probe their neural correlates. As predicted, conflict problems were associated with greater activation in the ACC-a key region for conflict detection-even in cases when participants responded stereotypically. In participants with higher CRT scores, conflict problems were associated with greater activation in the posterior cingulate cortex (PCC), and activation in PCC covaried in relation to CRT scores during conflict problems. Also, CRT scores predicted activation in PCC in conflict problems (over and above nonconflict problems). Our results suggest that individual differences in reflective thinking as measured by CRT are related to brain activation in PCC-a region involved in regulating attention between external and internal foci. We discuss the implications of our findings in terms of PCC's possible involvement in switching from intuitive to analytic mode of thought.

Structural correlates of Openness and Intellect: Implications for the contribution of personality to creativity.

Openness/Intellect (i.e., openness to experience) is the Big Five personality factor most consistently associated with individual differences in creativity. Recent psychometric evidence has demonstrated that this factor consists of two distinct aspects-Intellect and Openness. Whereas Intellect reflects perceived intelligence and intellectual engagement, Openness reflects engagement with fantasy, perception, and aesthetics. We investigated the extent to which Openness and Intellect are associated with variations in brain structure as measured by cortical thickness, area, and volume (N = 185). Our results demonstrated that Openness was correlated inversely with cortical thickness and volume in left middle frontal gyrus (BA 6), middle temporal gyrus (MTG, BA 21), and superior temporal gyrus (BA 41), and exclusively with cortical thickness in left inferior parietal lobule (BA 40), right inferior frontal gyrus (IFG, BA 45), and MTG (BA 37). When age and sex were statistically controlled for, the inverse correlations between Openness and cortical thickness remained statistically significant for all regions except left MTG, whereas the correlations involving cortical volume remained statistically significant only for left middle frontal gyrus. There was no statistically significant correlation between Openness and cortical area, and no statistically significant correlation between Intellect and cortical thickness, area, or volume. Our results demonstrate that individual differences in Openness are correlated with variation in brain structure-particularly as indexed by cortical thickness. Given the involvement of the above regions in processes related to memory and cognitive control, we discuss the implications of our findings for the possible contribution of personality to creative cognition.

Topographical memory for newly-learned maps is differentially affected by route-based versus landmark-based learning: a functional MRI study.

Humans rely on topographical memory to encode information about spatial aspects of environments. However, even though people adopt different strategies when learning new maps, little is known about the impact of those strategies on topographical memory, and their neural correlates. To examine that issue, we presented participants with 40 unfamiliar maps, each of which displayed one major route and three landmarks. Half were instructed to memorize the maps by focusing on the route, whereas the other half memorized the maps by focusing on the landmarks. One day later, the participants were tested on their ability to distinguish previously studied 'old' maps from completely unfamiliar 'new' maps under conditions of high and low working memory load in the functional MRI scanner. Viewing old versus new maps was associated with relatively greater activation in a distributed set of regions including bilateral inferior temporal gyrus - an important region for recognizing visual objects. Critically, whereas the performance of participants who had followed a route-based strategy dropped to chance level under high working memory load, participants who had followed a landmark-based strategy performed at above chance levels under both high and low working memory load - reflected by relatively greater activation in the left inferior parietal lobule (i.e. rostral part of the supramarginal gyrus known as area PFt). Our findings suggest that landmark-based learning may buffer against the effects of working memory load during recognition, and that this effect is represented by the greater involvement of a brain region implicated in both topographical and working memory.

One-way traffic: The inferior frontal gyrus controls brain activation in the middle temporal gyrus and inferior parietal lobule during divergent thinking.

Contrary to earlier approaches that focused on the contributions of isolated brain regions to the emergence of creativity, there is now growing consensus that creative thought emerges from the interaction of multiple brain regions, often embedded within larger brain networks. Specifically, recent evidence from studies of divergent thinking suggests that kernel ideas emerge in posterior brain regions residing within the semantic system and/or the default mode network (DMN), and that the prefrontal cortex (PFC) regions within the executive control network (ECN) constrain those ideas for generating outputs that meet task demands. However, despite knowing that regions within these networks exhibit interaction, to date the direction of the relationship has not been tested directly. By applying Dynamic Causal Modeling (DCM) to fMRI data collected during a divergent thinking task, we tested the hypothesis that the PFC exerts unidirectional control over the middle temporal gyrus (MTG) and the inferior parietal lobule (IPL), vs. the hypothesis that these two sets of regions exert bidirectional control over each other (in the form of feedback loops). The data were consistent with the former model by demonstrating that the right inferior frontal gyrus (IFG) exerts unidirectional control over MTG and IPL, although the evidence was somewhat stronger in the case of the MTG than the IPL. Our findings highlight potential causal pathways that could underlie the neural bases of divergent thinking.

Transfer of training from one working memory task to another: behavioural and neural evidence.

N-back working memory (WM) tasks necessitate the maintenance and updating of dynamic rehearsal sets during performance. The delayed matching-to-sample (dMTS) task is another WM task, which in turn involves the encoding, maintenance, and retrieval of stimulus representations in sequential order. Because both n-back and dMTS engage WM function, we hypothesized that compared to a control task not taxing WM, training on the n-back task would be associated with better performance on dMTS by virtue of training a shared mental capacity. We tested this hypothesis by randomly assigning subjects (N = 43) to train on either the n-back (including 2-back and 3-back levels) or an active control task. Following training, dMTS was administered in the fMRI scanner. The n-back group performed marginally better than the active control group on dMTS. In addition, although the n-back group improved more on the less difficult 2-back level than the more difficult 3-back level across training sessions, it was improvement on the 3-back level that accounted for 21% of the variance in dMTS performance. For the control group, improvement in training across sessions was unrelated to dMTS performance. At the neural level, greater activation in the left inferior frontal gyrus, right posterior parietal cortex, and the cerebellum distinguished the n-back group from the control group in the maintenance phase of dMTS. Degree of improvement on the 3-back level across training sessions was correlated with activation in right lateral prefrontal and motor cortices in the maintenance phase of dMTS. Our results suggest that although n-back training is more likely to improve performance in easier blocks, it is improvement in more difficult blocks that is predictive of performance on a target task drawing on WM. In addition, the extent to which training on a task can transfer to another task is likely due to the engagement of shared cognitive capacities and underlying neural substrates-in this case WM.

Neuroanatomical correlates of categorizing emotional valence.

Categorization is fundamental to cognition, and evidence suggests that categorizing emotional stimuli holds a privileged position in human information processing. According to theories on embodied emotion, the subjective emotional feeling elicited by a stimulus plays a causal role in its categorization. Using functional MRI, we tested the hypothesis that categorizing emotional stimuli in terms of valence would activate structures involved in valence-specific experience of emotion. On each trial, two pictures from the International Affective Picture System were presented successively. Upon viewing the second picture, participants categorized it as belonging to the same valence category as or a different valence category from the first picture. Categorization activated an exclusively left-lateralized set of regions implicated in taxonomic categorization (i.e. judging whether two items are of the same kind) including the middle temporal gyrus and precuneus, as well as the posterior cingulate cortex. Critically, for negative pictures categorization activated structures that underlie the experience of negative emotions (anterior insula, left orbitofrontal cortex), whereas for positive pictures categorization activated structures that underlie the experience of positive emotions (dorsomedial and ventromedial prefrontal cortex). Consistent with predictions derived from theories on embodied emotion, these results suggest that experience of emotion contributes to categorizing emotional valence.