The Effects of Selective Cholinergic Basal Forebrain Lesions and Aging upon Expectancy in the Rat

The effects of selective cholinergic cell loss within the basal forebrain (BF) were determined using a task that requires shifting of attention between two visual stimuli. Discriminability between two stimuli and response bias were determined in young and old F-344 rats given BF injections of IgG-192 saporin (100 ng). The lesion reduced ChAT activity in the frontal and parietal cortices, hippocampus, and olfactory bulbs. The lesion did not significantly alter Na⁺/K⁺-ATPase activity in cortex, hippocampus, or olfactory bulbs, or endogenous levels of neuropeptide Y and neurokinin B within the BF. The BF lesions impaired both stimulus discriminability and response bias in young and old rats. The BF lesions had a significantly greater effect upon stimulus discriminability and response bias in aged rats, compared to young rats, only when the stimulus duration was very brief, i.e., when the task was most difficult to solve. At longer stimulus durations, aging and lesions showed no interaction. The results suggest that the selective loss of cholinergic cells in the BF, but not normal aging, impairs the ability to discriminate between independent sensory stimuli. The loss of these cells confers a response bias in simple operant tasks involving motor responses to reward-related visual stimuli.     

Ear asymmetries on a selective attentional task

To ascertain whether there are ear-hemisphere asymmetries of selective attention, signal stimuli (tonal sequences) were presented monaurally with and without complex maskers (music and speech). The right ear-left hemisphere was more disrupted by language maskers; the left ear-right hemisphere was more disrupted by music maskers. These results suggest that there are hemispheric asymmetries of selective attention and that the ear hemisphere that usually processes a class of stimuli has greater difficulty filtering out those stimuli than does the nonspecialized hemisphere.     

Cognitive Heuristics and AIDS Risk Assessment Among Physicians1

Physicians (N= 331) reported perceived risk of HIV exposure, worry about on-the-job HIV exposure, and experience with patients who test seropositive for the HIV. In addition, the use of the availability heuristic was examined by responses to questions about talking and reading about AIDS, and the use of the simulation heuristic was examined by responses to questions about imagining oneself being exposed to HIV on the job. Simulation of the HIV-exposure experience related significantly to perceived risk (p < .001), even after variance attributable to actual experience and use of the availability heuristic was taken into account. Availability of AIDS information related marginally to perceived risk after variance attributable to actual experience and use of the simulation heuristic was taken into account. Simulation related strongly with worry about on-the-job exposure (p < .001), and availability was not significantly related to worry after variance associated with simulation and experience with AIDS was removed. Implications of these results for physician training are discussed.     

Anomalous Evidence,Confidence Change,and Theory Change

A novel experimental paradigm that measured theory change and confidence in participants' theories was used in three experiments to test the effects of anomalous evidence. Experiment 1 varied the amount of anomalous evidence to see if “dose size” made incremental changes in confidence toward theory change. Experiment 2 varied whether anomalous evidence was convergent (of multiple types) or replicating (similar finding repeated). Experiment 3 varied whether participants were provided with an alternative theory that explained the anomalous evidence. All experiments showed that participants' confidence changes were commensurate with the amount of anomalous evidence presented, and that larger decreases in confidence predicted theory changes. Convergent evidence and the presentation of an alternative theory led to larger confidence change. Convergent evidence also caused more theory changes. Even when people do not change theories, factors pertinent to the evidence and alternative theories decrease their confidence in their current theory and move them incrementally closer to theory change.     

Positive Contact with Feminist Women as a Predictor of Feminist Solidarity,Gender Privilege Awareness,and Public and Domestic Support for Gender Equality in Straight Men

Men can play an important role in supporting gender equality. In the present research, we draw on Intergroup Contact Theory to examine positive intergroup contact with feminist women as one factor that can encourage men to support gender equality. In one cross-sectional study (N?=?170) and one half-longitudinal panel study (N?=?240), we found that straight men who reported more positive contact with feminist women also reported greater feminist solidarity. Cross-sectional results indicated that straight men’s solidarity with feminists, in turn, predicted more support for gender equality in public and domestic spheres and greater awareness of their gender privilege. The longitudinal results also supported the association between solidarity with feminists and gender privilege awareness, but not public and domestic support for gender equality. Decades of research has shown that positive intergroup contact can change attitudes. Our research suggests that, when it comes to gender equality, positive contact with feminist women may also encourage men to identify with feminists and raise their gender consciousness.

     

Acute Intellectual Effects of Pediatric Head Trauma

The current study compared Wechsler Intelligence Scale for Children-III (WISC-III) performances of 30 children who sustained head injury with the performance of orthopedic controls matched on gender, age, race, and parental education and occupational attainment. Children were followed during initial hospitalization, trauma severity variables were recorded, and duration of posttraumatic amnesia (PTA) was determined by serial testing of mental status. The WISC-III was administered immediately following resolution of amnesia. Although the majority of patients sustained mild injuries, children with head injuries obtained significantly lower IQ and factor scores than nonneurologically injured children. Consistent with past research, performance-based scores including Performance IQ, Perceptual Organization, and Processing Speed were more sensitive to head trauma than their verbal counterparts. Standardized measurement of PTA appeared to be a better predictor of IQ status following injury than Glasgow Coma Scale score on admission or length of unconsciousness.     

Testing the limits of testing effects using completion tests

Recent work on testing effects has shown that retrieval practice can facilitate memory even for complex prose materials (Roediger & Karpicke, 2006a, 2006b). In three experiments the current study explores the effectiveness of retrieval practice on fill-in-the-blank (FITB) tests requiring the recall of specific words or phrases from a text. Final tests included both repeated items that were directly taken from initial tests, and related items. In Experiment 1, with a 2-day delay between initial and final tests, FITB testing benefited performance only on repeated items. In Experiment 2 a 7-day delay between testing sessions led to more robust effects on repeated items. However, once again no benefits were seen for related items. In Experiment 3 the scope of retrieval was varied by comparing FITB tests to paragraph recall tests requiring retrieval of all sentences following a topic sentence. Only the more open-ended recall practice demonstrated improvements in transfer to novel questions. The results suggest that scope or type of processing required during retrieval practice is likely a critical factor in whether testing will have specific or robust benefits.