The dopamine hypothesis of aging suggests that a monotonic dopaminergic decline accounts for many of the changes found in cognitive aging. The authors tested 44 older adults with a probabilistic selection task sensitive to dopaminergic function and designed to assess relative biases to learn more from positive or negative feedback. Previous studies demonstrated that low levels of dopamine lead to avoidance of those choices that lead to negative outcomes, whereas high levels of dopamine result in an increased sensitivity to positive outcomes. In the current study, age had a significant effect on the bias to avoid negative outcomes: Older seniors showed an enhanced tendency to learn from negative compared with positive consequences of their decisions. Younger seniors failed to show this negative learning bias. Moreover, the enhanced probabilistic integration of negative outcomes in older seniors was accompanied by a reduction in trial-to-trial learning from positive outcomes, thought to rely on working memory. These findings are consistent with models positing multiple neural mechanisms that support probabilistic integration and trial-to-trial behavior, which may be differentially impacted by older age.

Source memory has consistently been associated with prefrontal function both in normal and clinical populations. Nevertheless, the exact contribution of prefrontal cortex to source memory remains uncertain, and evidence suggests that processes engaged by young and older adults may differ. We explored the extent to which composite measures of frontal and medial temporal function differentially predicted the performance of young and older adults on source memory tasks. Results indicated that the frontal composite, which has consistently been associated with source memory performance in older adults, was unrelated to source memory in young adults, although it was sensitive to a demanding working memory task. The memory composite, however, predicted performance in the young group. In addition, item and source memory were correlated in young people but not in older people. Findings are discussed in terms of age-related differences in working memory and executive functions, and differential binding processes necessary for item and source memory. The requirement to integrate item and source information at encoding appears to place greater demands on executive or working memory processes in older adults than in younger.Keywords source memory; neuropsychology; frontal function; young adults; older adults Although source memory was initially defined narrowly as memory for the origin of information, more recently the construct has been used broadly to include any aspects of context associated with an event, including spatiotemporal, perceptual or affective attributes (Johnson, Hashtroudi, & Lindsay, 1993). Distinctions between content and context, however, are not straightforward, often depending on situational factors or an individual's goals. For these reasons, source has often been defined operationally in terms of the mapping between items and sources and experimenter instructions. In most experimental studies of source memory, there is a many-to-few mapping of items to sources: many sentences spoken in two voices, many concepts perceived or imagined, many objects in two locations or colors, or many words in one of two lists (e.g., Davidson & Glisky, 2002;Dodson & Shimamura, 2000;Glisky, Polster & Routhieaux, 1995;Henkel, Johnson, & DeLeonardis, 1998;Kuo & Van Petten, 2006). The many different stimuli (e.g., sentences) are defined as content, whereas the repeating aspects (e.g., two different voices) are defined as source or context. In addition, instructions or orienting tasks usually focus people's attention on the central content or item (cf., Chalfonte & Johnson, 1996). Notably, the type of materials need not define item and source; rather the nature of the task and instructions conveys such information. Thus, for example, if people hear many voices Send correspondence to: Elizabeth L. Glisky, Ph.D., Department of Psychology, 1503 E. University Blvd., University of Arizona, Tucson, AZ 85721, Email: glisky@u.arizona NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript speaking one of t...

Research has demonstrated differences in social and cognitive processes between East Asians and European Americans. Whereas East Asians have been characterized as being more sensitive to situational context and attending more to the perceptual field, European Americans have been characterized as being more focused on the object and being more field independent. The goal of the present experiment was to investigate differences in neural responses to target objects and stimulus context between East Asian Americans and European Americans using a three-stimulus novelty P3 event-related potential design. As hypothesized, European Americans displayed relatively greater target P3 amplitudes, indexing attention to target events, whereas East Asian Americans displayed relatively greater novelty P3 amplitudes, indexing attention to contextually deviant events. Furthermore, the authors found that interdependent self-construal mediated the relationship between culture and the novelty P3. These findings identify a specific pattern of neural activity associated with established cultural differences in contextual sensitivity.

Controversy surrounding dissociative identity disorder (DID) has focused on conflicting findings regarding the validity and nature of interidentity amnesia, illustrating the need for objective methods of examining amnesia that can discriminate between explicit and implicit memory transfer. In the present study, the authors used a cross-modal manipulation designed to mitigate implicit memory effects. Explicit memory transfer between identities was examined in 7 DID participants and 34 matched control participants. After words were presented to one identity auditorily, the authors tested another identity for memory of those words in the visual modality using an exclusion paradigm. Despite self-reported interidentity amnesia, memory for experimental stimuli transferred between identities. DID patients showed no superior ability to compartmentalize information, as would be expected with interidentity amnesia. The cross-modal nature of the test makes it unlikely that memory transfer was implicit. These findings demonstrate that subjective reports of interidentity amnesia are not necessarily corroborated by objective tests of explicit memory transfer.

The majority of Louisiana’s wild crayfish landings are harvested from the Atchafalaya River Basin (ARB) during floodplain inundation from the annual flood pulse. Spatial and temporal heterogeneity in ARB physicochemical characteristics are associated with flood pulse characteristics and floodplain inundation, and extensive areas of the ARB experience environmental hypoxia (dissolved oxygen [DO] < 2.0 mg·L-1) for several weeks to months during the annual flood pulse. The purpose of this research was to evaluate the effects of flood pulse characteristics and physicochemistry on harvested crayfish populations at 14 sites in the ARB that were sampled biweekly during the 2016 and 2017 crayfish seasons. Despite dissimilar 2016 and 2017 flood pulse characteristics, red swamp crawfish Procambarus clarkii and southern white river crawfish P. zonangulus carapace length and CPUE were similar between sample years. Comparisons of P. clarkii populations among physicochemical location groupings indicated that DO concentration, particularly chronically hypoxic water, is the principal abiotic variable influencing P. clarkii population characteristics. Although not significant, normoxic locations produced larger crayfish and yielded higher CPUE values for the majority of both crayfish seasons. Furthermore, hemolymph protein concentrations in P. clarkii from normoxic areas were significantly and consistently higher than individuals from chronically hypoxic locations.