The canine sand maze: an appetitive spatial memory paradigm sensitive to age-related change in dogs

Aged dogs exhibit a spectrum of cognitive abilities including a syndrome similar to Alzheimer's disease. A major impediment to research so far has been the lack of a quick and accurate test of visuospatial memory appropriate for community-based animals. We therefore report on the development and validation of the Canine Sand Maze. A 4.5-m-diameter circular pool was filled with a sand and powdered food reward mix to a depth of 10 cm. Dogs were given 4 habituation and 16 learning trials which alternated a food reward being half (control trials) or fully-buried (acquisition trials) in a fixed location. After a 90-min break, a probe trial was conducted. Cognitively normal, aged (> 8 years, n = 11) and young (1-4 years, n = 11), breed-matched dogs were compared. After correction for differences in control trials, average probe times were 2.97 and 10.81 s for young and aged dogs, respectively. In the probe trial, both groups spent significantly more time in the target quadrant but there was a trend for young dogs to cross a 1 m(2) annulus zone around the buried reward more frequently (2.6 times) than aged dogs (1.5 times). Test-retest reliability in a subset of young dogs (n = 5) was high. On the basis of these findings, the Canine Sand Maze is presented as a quick, sensitive and nonaversive tool for assessing spatial learning and reference memory in dogs.     

Power and status differentials in minority and majority group relations

Using a variant of the minimal group paradigm (Tajfel and Turner, 1986), this study tested the effects of power, status and group numbers on intergroup behaviours and perceptions. Subjects (N = 160) were categorized into groups that varied on status (high or low), power (dominant or subordinate) and group numbers (majority or minority) variables within a 2 × 2 × 2 experimental design. Based on their evaluations of others' creative products, subjects distributed credit points to ingroup and outgroup others using the Tajfel matrices. Results showed that dominant group members were much more discriminatory and less parity oriented towards outgroup others than subordinate group members. High status group members were more discriminatory and less parity oriented than low status group members. Minority group members who were dominant and of high status were highly discriminatory and were unique in showing no parity whatsoever towards outgroup others. Subordinate low status minorities did not discriminate and were exceptional in showing out-group favouritism. Relative to group status and group numbers, group power seemed more predictive of actual discriminatory behaviour. Group status accounted for the greatest variance in social identification and intergroup perceptions measures. Results also showed that social categorization was sufficient to elicit more in-group than outgroup liking amongst all group members regardless of their position in the intergroup structure. Overall, this study indicated that power, status and group numbers independently and in combination, have a strong impact on intergroup behaviours and perceptions.     

CLOSE RELATIONSHIPS AS SOURCES OF STRENGTH OR OBSTACLES FOR MOTHERS COPING WITH HIV

The current study explores the impact of HIV disease on the interpersonal relationships and social support experiences of mothers living with HIV. Analysis of interviews with 25 mothers with HIV focused on their perceptions of the impact of HIV on close relationships with significant others, including family of origin, children, friends, intimate partners, and parents. The results revealed the following major relationship challenges that mothers had to cope with after the discovery of their HIV-positive status: weighing reasons for and against disclosure of their HIV status, whether HIV disclosure brings relationship partners closer together, finding future caregivers for young children if one's health declines, and coordinating safer-sex practices with sexual partners, especially with the many males who are reluctant to use condoms. The study suggests the importance of understanding both the positive and negative aspects of social interactions in coping with HIV and the struggles that mothers have with the consequences of the HIV diagnosis for both themselves and their significant others.     

Minimal majorities and minorities

This study is one of a series of experiments designed to examine how sociostructural factors such as group numbers, power and status affect intergroup behaviour. Using a variant of Tajfel's ‘minimal group’ paradigm the present study investigated the intergroup behaviour of college students categorized as numerical minority, majority or ‘equal’ group members. The effects of salient (S) versus non-salient (S?) group categorizations were also examined. These manipulations yielded a 3 × 2 design matrix consisting of majority/equal/minority × salient (S)/non-salient (S?) group conditions. Unlike most previous studies using this paradigm, subjects' responses on Tajfel's point distribution matrices were supplemented with subjects' report of their own and outgroup's point distribution strategies. As expected, minimal group results were replicated in the ‘equal’ group (S?) condition such that mere categorization into ingroup/outgroup was sufficient to foster intergroup discrimination. However salient (S) equal group members were more fair than discriminatory in their responses. Minorities (S/S?) were generally less fair than equal groups, showed high levels of absolute ingroup favouritism (S?) while simultaneously attempting to establish positive distinctiveness from majorities. Though majorities were generally fair (S/S?), they also appeared to be more concerned than minorities about maintaining positive differentials between themselves and minorities. Although, majority (S/S?) and equal group (S?) members accurately reported their actual distribution strategies, minorities (S/S?) and equal (S) group members were not as accurate in their self reports. Overall the present results are consistent with hypotheses derived from Social Identity Theory. But the results also show that sociostructural variables such as group numbers can have an important impact on intergroup behaviours.     

Social categorization and power differentials in group relations

This study investigated the independent effects of power differentials on intergroup behaviour. Using a variant of Tajfel's minimal group paradigm (Tajfel and Turner, 1979), subjects were arbitrarily categorized into groups of differing power (0-100 per cent) at two levels of salience. Subjects were asked to distribute resources to ingroup and outgroup others using Tajfel's matrices. Intergroup perceptions, group identifications and self-reported strategies constituted our other dependent measures. Minimal group results, replicated in equal power conditions, were systematically eliminated in unequal power conditions on the matrix measures but not on the intergroup perception measures. Dominant group members were more discriminatory, felt more comfortable and satisfied than subordinate group members. Though consistent with Social Identity Theory (Tajfel and Turner, 1979), results suggest we may also have identified boundary conditions for minimal group discrimination. Without power, social categorization does not lead to effective discrimination.     

Status differenttals and intergroup behaviour

This study investigated the independent effects of status differential on intergroup behaviour. Using a variant of the minimal group paradigm (Tueland Turner, 1979), subjects were categorized into groups of differing status (high, equal, low) with two levels of category salience (high, low). Using Tajfel's matrices subjects rated the creativity of products ostensibly produced by ingroup and outgroup members. Own group identification, intergroup perceptions and self-reported strategies on the matrices constituted the other dependent measures. Results indicated a main effect for group status but none for salience. Equal status groups discriminated against each other thus replicating the minimal intergroup discrimination effect. High and equal status group members were more discriminatory against outgroups and more positive about their own group membership than were low status group members. In contrast, low status group members engaged in significant amounts of outgroup favouritism. Results also showed that social categorization per se was sufficient to elicit more ingroup than outgroup liking amongst all group members regardless of status differentials between groups. Overall, the results illustrate important aspects of the interplay between group status, social identity, prejudice and discrimination.     

Level of cognitive performance as a correlate and predictor of health behaviors that protect against cognitive decline in late life: The path through life study

There is a lack of information on how cognitive ability relates to both health behaviors and change in health behaviors over time. This study examined verbal ability and processing speed as predictors of health behaviors in the PATH Through Life Study that includes cohorts aged in their 20s, 40s and 60s. Higher cognitive scores were associated with higher levels of physical activity, greater likelihood of taking vitamin and mineral supplements, reduced likelihood of current smoking and not abstaining from alcohol. However, lower level of verbal ability and processing speed were associated with higher levels of use of cholesterol lowering medication in the 60s cohort. Physical activity, consumption of vitamins and minerals and taking cholesterol lowering and antihypertensive medication over the four-year follow-up period increased in this cohort. The likelihood of adopting healthier behaviors was greatest for those with the lowest cognitive scores. We conclude that while higher levels of cognitive performance are associated with health promoting behaviors, improvements in health behavior are more likely to be due to non-cognitive, contextual and societal factors.