Behavioral and neural predictors of upcoming decisions

Although it is widely known that brain regions such as the prefrontal cortex, the amygdala, and the ventral striatum play large roles in decision making, their precise contributions remain unclear. Here, we used functional magnetic resonance imaging and principles of reinforcement learning theory to investigate the relationship between current reinforcements and future decisions. In the experiment, subjects chose between high-risk (i.e., low probability of a large monetary reward) and low-risk (high probability of a small reward) decisions. For each subject, we estimated value functions that represented the degree to which reinforcements affected the value of decision options on the subsequent trial. Individual differences in value functions predicted not only trial-to-trial behavioral strategies, such as choosing high-risk decisions following high-risk rewards, but also the relationship between activity in prefrontal and subcortical regions during one trial and the decision made in the subsequent trial. These findings provide a novel link between behavior and neural activity by demonstrating that value functions are manifested both in adjustments in behavioral strategies and in the neural activity that accompanies those adjustments.     

Imaging recollection and familiarity in the medial temporal lobe: a three-component model

The medial temporal lobe (MTL) plays a crucial role in supporting memory for events, but the functional organization of regions in the MTL remains controversial, especially regarding the extent to which different subregions support recognition based on familiarity or recollection. Here we review results from functional neuroimaging studies showing that, whereas activity in the hippocampus and posterior parahippocampal gyrus is disproportionately associated with recollection, activity in the anterior parahippocampal gyrus is disproportionately associated with familiarity. The results are consistent with the idea that the parahippocampal cortex (located in the posterior parahippocampal gyrus) supports recollection by encoding and retrieving contextual information, whereas the hippocampus supports recollection by associating item and context information. By contrast, perirhinal cortex (located in the anterior parahippocampal gyrus) supports familiarity by encoding and retrieving specific item information. We discuss the implications of a 'binding of item and context' (BIC) model for studies of recognition memory. This model argues that there is no simple mapping between MTL regions and recollection and familiarity, but rather that the involvement of MTL regions in these processes depends on the specific demands of the task and the type of information involved. We highlight several predictions for future imaging studies that follow from the BIC model.     

Distinguishing automatic and controlled components of attitudes from direct and indirect measurement methods

Distinct automatic and controlled processes are presumed to influence social evaluation. Most empirical approaches examine automatic processes using indirect methods, and controlled processes using direct methods. We distinguished processes from measurement methods to test whether a process distinction is more useful than a measurement distinction for taxonomies of attitudes. Results from two studies suggest that automatic components of attitudes can be measured directly. Direct measures of automatic attitudes were reports of gut reactions (Study 1) and behavioral performance in a speeded self-report task (Study 2). Confirmatory factor analyses comparing two-factor models revealed better fits when self-reports of gut reactions and speeded self-reports shared a factor with automatic measures versus sharing a factor with controlled self-report measures. Thus, distinguishing attitudes by the processes they are presumed to measure (automatic versus controlled) is more meaningful than distinguishing based on the directness of measurement.     

Doubts about double dissociations between short- and long-term memory

Historically, psychologists and neuroscientists have distinguished between processes supporting memory for events across retention delays of several seconds (short-term memory, STM), and those supporting memory for events across longer retention delays of minutes or more (long-term memory, LTM). Dissociations reported in some neuropsychological studies have contributed to a popular view that there must be neurally distinct memory stores that differentially support STM and LTM. In this article, we review evidence from recent studies regarding dissociations between STM and LTM. We suggest that the evidence reveals problems with claims of selective STM or LTM impairments, which in turn questions whether theories of memory need to propose neurally distinct stores for short- and long-term retention. We consider alternative ways to explain the neural mechanisms of memory across different retention intervals.     

Correlates of relationship, psychological, and sexual behavioral factors for HIV risk among Indian women

The rate of HIV/AIDS among women in India is expected to rise yet few studies have examined factors related to HIV risk among Indian women. The objective of this prospective, cross-sectional study was to characterize similarities and differences in the relationships, psychological well-being, and sexual behaviors among Indian women (N=459). Both HIV positive (N=216) and negative (N=243) women from urban and rural areas in India were included in this study. Chi-square, analysis of variance, and logistic regression analyses revealed that in both geographic groups, HIV-positive women were significantly more likely to report marital dissatisfaction, a history of forced sex, domestic violence, depressive symptoms and husband's extra marital sex when compared to the HIV-negative women. Findings also indicate that specific factors related to the quality of the marital relationship such as domestic violence, martial dysfunction, and depressive symptoms may be related to HIV-related risks for women. Implications for future research and culturally relevant interventions are discussed.     

Neural correlates of person recognition

Rapidly identifying known individuals is an essential skill in human society. To elucidate the neural basis of this skill, we monitored brain activity while experimental participants demonstrated their ability to recognize people on the basis of viewing their faces. Each participant first memorized the faces of 20 individuals who were not known to the participants in advance. Each face was presented along with a voice simulating the individual speaking their name and a biographical fact. Following this learning procedure, the associated verbal information could be recalled accurately in response to each face. These learned faces were subsequently viewed together with new faces in a memory task. Subjects made a yes-no recognition decision in response to each face while also covertly retrieving the person-specific information associated with each learned face. Brain activity that accompanied this retrieval of person-specific information was contrasted to that when new faces were processed. Functional magnetic resonance imaging in 10 participants showed that several brain regions were activated during blocks of learned faces, including left hippocampus, left middle temporal gyrus, left insula, and bilateral cerebellum. Recordings of event-related brain potentials in 10 other participants tracked the time course of face processing and showed that learned faces engaged neural activity responsible for person recognition 300-600 msec after face onset. Collectively, these results suggest that the visual input of a recently learned face can rapidly trigger retrieval of associated person-specific information through reactivation of distributed cortical networks linked via hippocampal connections.     

Distinguishing highly confident accurate and inaccurate memory: insights about relevant and irrelevant influences on memory confidence

It is generally believed that accuracy and confidence in one's memory are related, but there are many instances when they diverge. Accordingly it is important to disentangle the factors that contribute to memory accuracy and confidence, especially those factors that contribute to confidence, but not accuracy. We used eye movements to separately measure fluent cue processing, the target recognition experience, and relative evidence assessment on recognition confidence and accuracy. Eye movements were monitored during a face-scene associative recognition task, in which participants first saw a scene cue, followed by a forced-choice recognition test for the associated face, with confidence ratings. Eye movement indices of the target recognition experience were largely indicative of accuracy, and showed a relationship to confidence for accurate decisions. In contrast, eye movements during the scene cue raised the possibility that more fluent cue processing was related to higher confidence for both accurate and inaccurate recognition decisions. In a second experiment we manipulated cue familiarity, and therefore cue fluency. Participants showed higher confidence for cue-target associations for when the cue was more familiar, especially for incorrect responses. These results suggest that over-reliance on cue familiarity and under-reliance on the target recognition experience may lead to erroneous confidence.     

Implicit attitude generalization occurs immediately; explicit attitude generalization takes time

People are able to explicitly resist using knowledge about one person to evaluate another person from the same group. After learning about positive and negative behaviors performed by one individual from each of two different groups, participants were introduced briefly to new individuals from the groups. Implicit evaluations of the original individuals readily generalized to the new individuals; explicitly, participants resisted such generalization. Days later, both implicit and explicit evaluations of the original individuals generalized to the new individuals. The results suggest that associative links (e.g., shared group membership) are sufficient for implicit attitude generalization, but deliberative logic (e.g., individual group members are not necessarily the same) can reduce explicit generalization by association. When knowledge distinguishing who did what is unavailable, such as after forgetting, associative knowledge provides the basis of explicit evaluation. We conclude that a simple association linking one individual to another can produce implicit attitude generalization immediately and explicit attitude generalization eventually.     

Pervasiveness and correlates of implicit attitudes and stereotypes

http://implicit.harvard.edu/ was created to provide experience with the Implicit Association Test (IAT), a procedure designed to measure social knowledge that may operate outside awareness or control. Significant by-products of the website's existence are large datasets contributed to by the site's many visitors. This article summarises data from more than 2.5 million completed IATs and self-reports across 17 topics obtained between July 2000 and May 2006. In addition to reinforcing several published findings with a heterogeneous sample, the data help to establish that: (a) implicit preferences and stereotypes are pervasive across demographic groups and topics, (b) as with self-report, there is substantial inter-individual variability in implicit attitudes and stereotypes, (c) variations in gender, ethnicity, age, and political orientation predict variation in implicit and explicit measures, and (d) implicit and explicit attitudes and stereotypes are related, but distinct.