The information content of panoramic images II: view-based navigation in nonrectangular experimental arenas

Two recent studies testing navigation of rats in swimming pools have posed problems for any account of the use of purely geometric properties of space in navigation (M. Graham, M. A. Good, A. McGregor, & J. M. Pearce, 2006; J. M. Pearce, M. A. Good, P. M. Jones, & A. McGregor, 2004). The authors simulated 1 experiment from each study in a virtual reality environment to test whether experimental results could be explained by view-based navigation. The authors recorded a reference image at the target location and then determined global panoramic image differences between this image and images taken at regularly spaced locations throughout the arena. A formal model, in which an agent attempts to minimize image differences between the reference image and current views, generated trajectories that could be compared with the search performance of rats. For both experiments, this model mimics many aspects of rat behavior. View-based navigation provides a sufficient and parsimonious explanation for a range of navigational behaviors of rats under these experimental conditions.     

Event-related potentials, reaction time, and response selection of skilled and less-skilled cricket batsmen

The differences in P300 latency, P300 amplitude, response selection, and reaction time between skilled and less-skilled cricket batsmen have been investigated. Eight skilled and ten less-skilled right-handed batsmen each viewed 100 in-swing, 100 out-swing, and 40 slower deliveries displayed in random sequence from projected video footage whilst their responses and electroencephalograms were recorded. Logistic regression was used to derive a discriminative function for the P300 data. This was done to determine whether the skilled batsmen differed from the less-skilled batsmen on the basis of pooled P300 amplitude and latency data. All the batsmen were correctly characterised as being skilled or less-skilled. Logistic regression equations with reaction time and correctness of response data indicated that behavioural data do not correctly classify skilled performance. It is suggested that skilled cricket batsmen have a superior perceptual decision-making ability compared with less-skilled cricket batsmen, as measured by P300 latency and amplitude. This appears to be the first study showing a link between skill and cerebral cortical activity during a perceptual cricket batting task and it could pave the way for future studies on mental processing in cricket batsmen.     

On some limits of hypothetical thinking

Faced with extreme demands, hypothetical thinking runs the danger of total failure. Paradoxical propositions such as the Liar (“I am lying”) provide an opportunity to test it to its limits, while the Liar's nonparadoxical counterpart, the Truthteller (“I am telling the truth”), provides a useful comparison. Two experiments are reported, one with abstract materials (“If I am a knave then I live in Emerald City”) and one with belief-laden materials (a judge says: “If I am a knave then I enjoy pop music”). In both experiments, conditionals with Truthteller-type antecedents were “collapsed” to responses of conditional probability closely resembling estimates of control items. Liar-type antecedents, in contrast, dramatically weakened belief in conditionals in which they were embedded. The results are discussed in the framework of the theory of hypothetical thinking.     

Remembering the past and imagining the future in schizophrenia

It has been suggested that patients with schizophrenia experience a distorted sense of continuity of self across time. However, temporal aspects of self-processing have received little empirical attention in schizophrenia. In this study, the authors investigated schizophrenic patients' ability to generate specific mental images of their personal past and future. Results showed that patients recalled fewer specific past events than did healthy controls and were even more impaired in generating specific future events. These deficits were associated with positive symptoms but were not associated with negative symptoms or with performances on verbal fluency tasks. It is suggested that schizophrenic patients' failures to project themselves into specific past and future episodes might be related to difficulties in retrieving contextual details from memory, as well as disturbance of the sense of subjective time.     

When can we say 'if'?

In this study, we focus on the conditions which permit people to assert a conditional statement of the form 'if p then q' with conversational relevance. In a broadly decision-theoretic approach, also drawing on hypothetical thinking theory [Evans, J. St. B. T. (2007). Hypothetical thinking: Dual processes in reasoning and judgement. Hove, UK: Psychology Press.], we predicted that conditional tips and promises would appear more useful and persuasive and be more likely to encourage an action p when (a) the conditional link from p to q was stronger, (b) the cost of the action p was lower and (c) the benefit of the consequence q was higher. Similarly, we predicted that conditional warnings and threats would be seen as more useful and persuasive and more likely to discourage an action p when (a) the conditional link from p to q was stronger, (b) the benefit of the action p was lower and (c) the cost of the consequence q was higher. All predictions were strongly confirmed, suggesting that such conditionals may best be asserted when they are of high relevance to the goals of the listener.     

Directed forgetting and aging: the role of retrieval processes, processing speed, and proactive interference

The directed forgetting effect obtained with the item method is supposed to depend on both selective rehearsal of to-be-remembered (TBR) items and attentional inhibition of to-be-forgotten (TBF) items. In this study, we investigated the locus of the directed forgetting deficit in older adults by exploring the influence of recollection and familiarity-based retrieval processes on age-related differences in directed forgetting. Moreover, we explored the influence of processing speed, short-term memory capacity, thought suppression tendencies, and sensitivity to proactive interference on performance. The results indicated that older adults' directed forgetting difficulties are due to decreased recollection of TBR items, associated with increased automatic retrieval of TBF items. Moreover, processing speed and proactive interference appeared to be responsible for the decreased recall of TBR items.     

Rethinking Social Participation: The Case of Immigrants in Canada

The social engagement of Canada’s immigrants continues to be the subject of debates. Most studies indicate a lower level of involvement, particularly for recent immigrants. This article investigates the possible causes of this lower participation by analyzing data from the 1998 General Social Survey (GSS), which provides precise measures of two different types of social engagement: volunteering and social participation. Three results stand out. First, formal volunteering and broader social participation do not display the same level of variability across groups. Second, the positive family effect usually observed does not apply to immigrants: the presence of children does not significantly increase their social engagement. Third, there is a strong gender component: whereas Canadian women are more likely to participate, immigrant women are not. Other factors (age, income, education), on the other hand, do seem to apply to both groups. We suggest that these results contribute to a new explanation of immigrant social engagement: Rather than being marked by a general immigration differential, newcomers to Canada seem to be left out of very specific, gender-influenced modes of participation, specifically, those related to the family, children, and schooling.     

Assessing Violence Risk: A Review and Clinical Recommendations

Guidance to identify and manage clients with a perceived high risk for future violence is of great importance for mental health professionals. In the past decade, several structured instruments have been developed to assess risk of future violence. Awareness of the limits and abilities of such instruments is required. This article reviews the most well‐known risk assessment tools and provides recommendations for how to approach the area of violence risk assessment.     

Depressive symptoms in early marriage: predictions from relationship confidence and negative marital interaction.

The authors proposed a model of depressive symptoms in early marriage in which relationship confidence, defined as perceived couple-level efficacy to manage conflicts and maintain a healthy relationship, mediates the effect of negative marital interactions on depressive symptoms. The model was tested in a sample of 139 couples assessed prior to marriage and 1 year later. As predicted, relationship confidence demonstrated simple negative associations with negative marital interaction and depressive symptoms for all participants. Longitudinal path analyses supported the mediational model for women only. In women but not men, negative marital interaction indirectly had an impact on depressive symptoms through the mediator of relationship confidence. Findings suggest that relationship confidence may be important to understanding links between marital distress and depressive symptoms, especially in women.