The effects of Δ9 THC on cutaneous sensitivity and its relation to personality

Pain threshold/tolerance and vibration perception were studied in a sample of female frequent and infrequent cannabis users. Interactions with personality characteristics were examined using the EPI. Performance on all measures was investigated after oral administration of either 10mgΔ⁹ THC or 20 mg Δ⁹ THC. Results indicated that while the 10mg dosage produced no consistent changes in cutaneous sensory response, the 20 mg dosage was followed by lowering of the vibration threshold. Frequent and infrequent cannabis users differed in their response to the pain stimulus (pain tolerance scores were higher among infrequent users). They also differed with respect to the personality measure (frequent users had lower E, N and L scores). The findings provide experimental support for cannabis users' reports of enhanced sensory awareness consequent to drug intake. The results also show that frequent and infrequent cannabis users differ in pain response and personality characteristics.     

Ageing and lexical access to common and proper names in picture naming

The question of whether lexical access for proper names is more impaired by ageing than lexical acess for other words is controversial. The aim of the present investigation was to evaluate the effect of age on proper and common name retrieval in long-term memory. The word retrieval paradigm used to achieve this goal consisted of the naming of photographs representing celebrities (production of a certain kind of proper names: names of people) and objects (production of common names). Compared with younger adults, elderly people experienced more tip-of-the-tongue states for proper names, but not for common names. Thus, the present study provides support for disproportionate age-related problems in lexical access to proper names. This finding is interpreted with reference to the cognitive model of speech production proposed by Burke et al. (1991).     

Insidious dangers of benevolent sexism: consequences for women's performance

Four experiments found benevolent sexism to be worse than hostile sexism for women's cognitive performance. Experiments 1-2 showed effects of paternalist benevolent sexism and ruled out explanations of perceived sexism, context pleasantness, and performance motivation. Experiment 3 showed effects of both paternalist and complementary gender differentiation components of benevolent sexism. Benevolent sexism per se (rather than the provision of unsolicited help involved in paternalism) worsened performance. Experiment 4 showed that impaired performance due to benevolent sexism was fully mediated by the mental intrusions women experienced about their sense of competence. Additionally, Experiment 4 showed that gender identification protected against hostile but not benevolent sexism. Despite the apparently positive and inoffensive tone of benevolent sexism, our research emphasizes its insidious dangers.     

Incongruent object/context relationships in visual scenes: Where are they processed in the brain?

Rapid object visual categorization in briefly flashed natural scenes is influenced by the surrounding context. The neural correlates underlying reduced categorization performance in response to incongruent object/context associations remain unclear and were investigated in the present study using fMRI. Participants were instructed to categorize objects in briefly presented scenes (exposure duration = 100 ms). Half of the scenes consisted of objects pasted in an expected (congruent) context, whereas for the other half, objects were embedded in incongruent contexts. Object categorization was more accurate and faster in congruent relative to incongruent scenes. Moreover, we found that the two types of scenes elicited different patterns of cerebral activation. In particular, the processing of incongruent scenes induced increased activations in the parahippocampal cortex, as well as in the right frontal cortex. This higher activity may indicate additional neural processing of the novel (non experienced) contextual associations that were inherent to the incongruent scenes. Moreover, our results suggest that the locus of object categorization impairment due to contextual incongruence is in the right anterior parahippocampal cortex. Indeed in this region activity was correlated with the reaction time increase observed with incongruent scenes. Representations for associations between objects and their usual context of appearance might be encoded in the right anterior parahippocampal cortex.     

Does a yellow filter improve visual object categorization in normal aging?

Previous studies have shown that a yellow filter (CPF450) can increase contrast, motion sensitivity, vergence, and accommodation. We investigated whether a yellow filter can reduce age-related visual deficits. We tested two groups of 60 observers (mean age 24 vs. 72) in an object categorization task. Grayscale photographs of natural objects and artifacts were displayed either centrally or peripherally (21°) at low (8%) or medium (30%) contrast. There were three filter conditions (no filter, placebo filter, and yellow filter). Both groups of observers performed similarly on central and medium-contrast pictures. The deleterious effects of reduced contrast and eccentricity were stronger in elderly individuals. Moreover, the yellow filter globally improved the speed of categorization for the elderly participants. The decrease in response time in the yellow filter condition was larger when the stimuli were displayed peripherally in both groups. A yellow filter should be considered as a potential means for visual improvement in normal aging.