Spatial and nonspatial escape strategies in the Barnes maze

The Barnes maze is a spatial memory task that requires subjects to learn the position of a hole that can be used to escape the brightly lit, open surface of the maze. Two experiments assessed the relative importance of spatial (extra-maze) versus proximal visible cues in solving the maze. In Experiment 1, four groups of mice were trained either with or without a discrete visible cue marking the location of the escape hole, which was either in a fixed or variable location across trials. In Experiment 2, all mice were trained with the discrete visible cue marking the target hole location. Two groups were identical to the cued-target groups from Experiment 1, with either fixed or variable escape locations. For these mice, the discrete cue either was the sole predictor of the target location or was perfectly confounded with the spatial extra-maze cues. The third group also used a cued variable target, but a curtain was drawn around the maze to prevent the use of spatial cues to guide navigation. Probe trials with all escape holes blocked were conducted to dissociate the use of spatial and discrete proximal cues. We conclude that the Barnes maze can be solved efficiently using spatial, visual cue, or serial-search strategies. However, mice showed a strong preference for using the distal room cues, even when a discrete visible cue clearly marked the escape location. Importantly, these data show that the cued-target control version of the Barnes maze as typically conducted does not dissociate spatial from nonspatial abilities.     

Lesions of the dorsolateral or dorsomedial striatum impair performance of a previously acquired simple discrimination task

Previous evidence has suggested a specific role for the dorsal striatum, especially the dorsolateral region of the dorsal striatum, in stimulus-response learning. In a previous study, we found an impairment in animals with dorsolateral striatal lesions on a simple discrimination task (CS+/CS-), thought to require the involvement of both stimulus-reward and stimulus-response learning. It is possible that the generally poor performance of dorsolateral lesioned animals on this experiment precluded adequate exposure to stimulus-reward pairings necessary for solving this task, and, thus, had little to do with stimulus-response learning. To test this hypothesis, the performance of animals with dorsolateral and dorsomedial striatal lesions was assessed on a previously acquired simple discrimination task. To independently assess the effects of each lesion on the performance of stimulus-reward learning, dorsolateral and dorsomedial lesioned animals were assessed on a previously acquired conditioned place preference task (CPP). In agreement with our earlier experiment, and the stimulus-response interpretation of dorsolateral striatal function, animals with dorsolateral striatal lesions were found to be impaired during post-lesion performance of the simple discrimination task, but not CPP learning. Additionally, dorsomedial lesioned animals were found to be impaired in performance of the simple discrimination task, but not on the CPP task. Possible explanations for the differences between the role of the dorsomedial striatum in acquisition and expression of the simple discrimination task are proposed.     

A Model of Contagion Through Competition in the Aggressive Behaviors of Elementary School Students

This article extends the work of Kellam, Ling, Merisca, Brown and Ialongo (1998) by applying a mathematical model of competition between children to peer contagion in the aggressive behaviors of elementary school students. Nonlinearity in the relationship between group aggression and individual aggression at 2-year follow-up is present. Consistent with the findings of Kellam et al. (1998), hierarchical linear modeling indicates that the relationship is statistically significant for those students whose initial parental ratings of aggressive behavior were above the sample median. In the context of competition between students, the behavior of initially aggressive students may be negatively reinforced. Lowering aggression in the school environment may therefore be the most effective way to lower the level of these students aggressive behavior.     

Schema Theory: A Critical Appraisal and Reevaluation

The authors replicated and extended results from the gunfight paradigm (A. Welchman, J. Stanley, M. Schomers, R. Miall, & H. Bulthoff, 2010a) in which participants moved faster when reacting to the perceived initiation of an opponent compared to initiating an action themselves. In addition to replicating these movement time effects, the authors found that time to peak velocity, peak velocity, and movement-endpoint dispersions were similarly impacted. The findings are discussed in terms of a triggering mechanism involved in ballistic and internally generated movements.     

Connections Between Graphical Gaussian Models and Factor Analysis

Connections between graphical Gaussian models and classical single-factor models are obtained by parameterizing the single-factor model as a graphical Gaussian model. Models are represented by independence graphs, and associations between each manifest variable and the latent factor are measured by factor partial correlations. Power calculations for the single-factor graphical Gaussian model are facilitated by expressing the manifest partial correlations as functions of the factor partial correlations. The power of selecting a graphical Gaussian model with an association structure between manifest variables compatible with a single-factor model is investigated. The results are illustrated using 2 examples: the 1st is a hypothetical factor model with parallel measures. The 2nd uses data from the British Household Panel Survey on job satisfaction.     

Personality Characteristics of Freshman Medical Students as Depicted by the Leary System

Abstract

(Biber, B., Murphy, L. B., Woodcock, L. P., &; Black, I. S. Child Life in School: A Study of a Seven-Year-Old Group. New York: Dutton, 1942. Pp. 658.) Reviewed by Louise Bates Ames     

Repetition-lag training to improve recollection memory in older people with amnestic mild cognitive impairment. A randomized controlled trial

The results of a randomized controlled trial of repetition-lag training in older adults with amnestic mild cognitive impairment (aMCI) are reported. A modified repetition-lag training procedure with extended encoding time and strategy choice was used. The training required discriminating studied words from non-studied lures that were repeated at varying intervals during the test phase. Participants were assessed pre/post using untrained measures of cognition and self-report questionnaires. Primary outcome measures were recall of unrelated word pairs both immediately following presentation and following a delay. Secondary outcomes were a measure of attention, cognitive flexibility, and visual working memory. Participants were also asked to report on the frequency of cognitive failures and mood before and after training. Participants (N = 31) were randomized into either the treatment or a no-contact control group and attended the clinic twice per week over a four week period. Twenty-four participants completed the study (twelve in each group). Results indicated that the training group improved at recalling unrelated word pairs after a delay. There were no significant effects of training on other outcomes, self-reported cognitive failures or mood. The results are discussed along with suggestions for future research.     

Human risky choice in a repeated-gambles procedure: an up-linkage replication of Lakshminarayanan, Chen and Santos (2011)

Lakshminarayanan et al. (J Exp Soc Psychol 47: 689–693, 2011) showed that when choice is between variable (risky) and fixed (safe) food amounts with the same expected values, capuchins prefer the safe alternative if choice is framed as a gain, but the risky alternative if it is framed as a loss. These results seem similar to those seen in human prospect-theory tests in choice between variable and fixed gains or losses. Based on this similarity, they interpreted their results as identifying a between-species commonality in cognitive function. In this report, we repeat their experiment with humans as subjects (an up-linkage replication). Whether choices were rewarded with candy or nickels, choice approximated indifference whether framed as gains or losses. Our data mirror those of others who found that when humans make risky choices within a repeated-trials procedure without verbal instruction about outcome likelihoods, preference biases seen in one-shot, language-guided, prospect-theory tests such as Tversky and Kahneman’s (Science 211:453–458, 1981) reflection effect may not appear. The disparity between our findings and those of Lakshminarayanan et al. suggests their study does not evidence a cognitive process shared by humans and capuchins.     

Evidence for word length coding during visual word recognition

In a masked priming procedure manipulating orthographic neighbourhood size, the priming word activates a number of word candidates of which the target could be one. Whether the target is one of the candidates or not determines how quickly it is recognised. However, the efficiency of lexical processing may be markedly less if all possible candidates are activated. One solution to this problem is if the visual system uses prime length information to reduce the number of candidates to a more manageable amount. Here, we investigated in two masked priming experiments whether prime length and orthographic information combine to facilitate target word recognition. In Experiment 1, we showed that the efficiency of visual word recognition is not influenced by the length of primes alone. However, when combined with orthographically related primes, word length coding is preserved. In Experiment 2, we investigated whether length priming affects recognition of short and long words differently. Results showed that only short words benefit from a same-length orthographically related prime, and that the priming effect does not generalise to longer words. These results suggest that the length of a word is not an essential feature in lexical processing, but that it can facilitate recognition by constraining the activation of orthographically related words.     

The Masking Function of Self-Revelation in Group Therapy

Though similar to traditional group psychotherapy in many respects, a coping skill training approach differs principally in several areas and technically in many more. Coping skill training group therapy tends to employ many concrete intervention strategies to enhance various aspects of process, drawing on ongoing data to evaluate group interaction and individual responses. The approach draws more heavily on cognitive, modeling, reinforcement, and problem-solving procedures to achieve specifically determined goals, and it depends less on interpretive and confrontative methods. The author discusses a wide range of techniques to show the benefits of this approach.