Optimal Predictions in Everyday Cognition: The Wisdom of Individuals or Crowds?

Griffiths and Tenenbaum (2006) asked individuals to make predictions about the duration or extent of everyday events (e.g., cake baking times), and reported that predictions were optimal, employing Bayesian inference based on veridical prior distributions. Although the predictions conformed strikingly to statistics of the world, they reflect averages over many individuals. On the conjecture that the accuracy of the group response is chiefly a consequence of aggregating across individuals, we constructed simple, heuristic approximations to the Bayesian model premised on the hypothesis that individuals have access merely to a sample of k instances drawn from the relevant distribution. The accuracy of the group response reported by Griffiths and Tenenbaum could be accounted for by supposing that individuals each utilize only two instances. Moreover, the variability of the group data is more consistent with this small-sample hypothesis than with the hypothesis that people utilize veridical or nearly veridical representations of the underlying prior distributions. Our analyses lead to a qualitatively different view of how individuals reason from past experience than the view espoused by Griffiths and Tenenbaum.     

Human topological task adapted for rats: Spatial information processes of the parietal cortex

Human research has shown that lesions of the parietal cortex disrupt spatial information processing, specifically topological information. Similar findings have been found in non-humans. It has been difficult to determine homologies between human and non-human mnemonic mechanisms for spatial information processing because methodologies and neuropathology differ. The first objective of the present study was to adapt a previously established human task for rats. The second objective was to better characterize the role of parietal cortex (PC) and dorsal hippocampus (dHPC) for topological spatial information processing. Rats had to distinguish whether a ball inside a ring or a ball outside a ring was the correct, rewarded object. After rats reached criterion on the task (>95%) they were randomly assigned to a lesion group (control, PC, and dHPC). Animals were then re-tested. Post-surgery data show that controls were 94% correct on average, dHPC rats were 89% correct on average, and PC rats were 56% correct on average. The results from the present study suggest that the parietal cortex, but not the dHPC processes topological spatial information. The present data are the first to support comparable topological spatial information processes of the parietal cortex in humans and rats.     

Critical periods and catastrophic interference effects in the development of self-organizing feature maps

The use of self-organizing feature maps (SOFM) in models of cognitive development has frequently been associated with explanations of critical or sensitive periods. By contrast, error-driven connectionist models of development have been linked with catastrophic interference between new knowledge and old knowledge. We introduce a set of simulations that systematically evaluate the conditions under which SOFMs demonstrate critical/sensitive periods in development versus those under which they display interference effects. We explored the relative contribution of network parameters (for example, whether learning rate and neighbourhood reduce across training), the representational resources available to the network, and the similarity between old and new knowledge in determining the functional plasticity of the maps. The SOFMs that achieved the best discrimination and topographic organization also exhibited sensitive periods in development while showing lower plasticity and hence limited interference. However, fast developing, coarser SOFMs also produced topologically organized representations, while permanently retaining their plasticity. We argue that the impact of map organization on behaviour must be interpreted in terms of the cognitive processes that the map is driving.     

Reciprocal influences between maternal discipline techniques and aggression in children and adolescents

Most studies assessing the link between parental discipline and child aggression have focused primarily on discipline as a cause and aggression as an outcome. In addition to the pathway from discipline to aggression, however, aggressive behavior on the part of the child may lead to future use of discipline by the parent. In this study, structural equation modeling was used to assess reciprocal influences over time between a mothers' use of discipline and aggression in children. Data were drawn from the Springfield Child Development Project, a longitudinal study of middle childhood and adolescence, focusing on antecedents of aggression. The original sample consisted of 440 mother-child dyads living in the city of Springfield, MA. Children in the sample were between 7 and 14 years of age at the first data collection period and between 12 and 19 years of age at the final data collection period. Four hypotheses were tested: (1) a mother's use of aggressive discipline predicts an increase in later child aggression, (2) child aggression predicts an increase in later use of aggressive discipline, (3) the use of reasoning predicts a decrease in later child aggression, and (4) child aggression predicts an increase in later use of reasoning. All hypotheses except number 3 were supported to some degree. Results suggest that children's early aggressive behavior leads to an increase in their mothers' use of both reasoning and aggressive discipline; in turn, increased use of aggressive discipline leads to an increase in aggression during both childhood and adolescence.     

Approach, avoidance, and self-regulatory conflict: An individual differences perspective

Four studies involving 230 undergraduates examined the interactive effects of dispositional approach and avoidance, as manifest in the traits of extraversion and neuroticism. Participants who were high in both traits or low in both traits exhibited less assertive knocking behavior (Study 1), had difficulties refraining from blinking (Study 2), and displayed more anxious behavior during a mental health interview (Study 3). Study 4 tested the idea that such extraversion by neuroticism interactions might be associated with difficulties in recognizing and responding to goal-relevant stimuli. Results involving a go/no go task confirmed this hypothesis. In total, the results highlight the manner in which the co-activation of dispositional motives related to approach and avoidance can compromise effective self-regulation.     

Problematic effects of aggregation in z ROC analysis and a hierarchical modeling solution

The confidence-rating recognition memory paradigm has been used extensively for testing theories of memory. Current methods for analyzing confidence-rating data require that data be aggregated over participants, items, or both. We show that this aggregation threatens claims of curvature in zROCs and distorts estimates of signal-distribution variance—the very findings that are used to make fine-grained distinctions between competing models. We develop a hierarchical signal detection model that accounts for variability from the sampling of participants and items in addition to variability from the underlying psychological processes. The model provides for accurate signal detection parameter estimates. With accurate estimates, the validity of benchmark findings in recognition memory may be assessed.     

Dissociations in visual attention deficits among persons with mild cognitive impairment

Impairments in visual attention and visual information processing have been identified as part of the neuropsychological features of Alzheimer's disease (AD), even in its earliest stages. There is increasing recognition that these deficits may be selective rather than global, with some attentional subtypes being more vulnerable than others. The few studies that have investigated attentional deficits in mild cognitive impairment (MCI), a putatively prodromal phase of AD, have not satisfactorily addressed the possible selectivity in attentional deficits in MCI. This study examined potential dissociations in visual attention deficits in MCI using a measure that assesses simple, divided, and selective attention. The results indicated a hierarchy of attentional impairments, with divided attention being the most affected and simple attention the least. Among participants with MCI, 53% showed evidence of impairment in divided attention compared to 19% of controls (OR = 4.81, p < .001). Poorer visual attention was also associated with poorer overall cognitive status. The implications of these findings for early identification of MCI, prevention of functional decline in MCI, and delay/reversal of cognitive degradation in MCI are discussed.