Further Evidence that Social Interaction Reduces Conditioned Taste Aversions in Mice

Social interactions with other conspecifics affect food selection in mammals. A previous study suggested that male mice attenuate conditioned taste aversion (CTA) by lithium chloride after interacting with an unfamiliar male conspecific. The present study was designed to (a) examine whether interactions with a familiar conspecific would attenuate CTA and (b) investigate sex differences in the social attenuation of CTA in mice. Results indicated that interacting with a familiar conspecific of the same sex following poisoning attenuated conditioned taste aversions only in male mice. The results suggest that the familiarity of conspecifics was not a critical factor in the social attenuation of CTA. Discrepancies between present and previous findings are discussed.     

The apparent paths of two or three circularly moving spots

Summary Two or three circularly moving luminous spots presented side by side in a dark room were observed under non-restrictive conditions, instead of pursuing a particular spot with the eyes. The experimental variables were speed, direction (clockwise or counterclockwise) and the phase difference between the moving spots. The paths of the circularly moving spots appeared to be a circle, an ellipse, or a straight line. With the three phase differences of 0°, 90°, and 180°, the paths appeared to be horizontally, obliquely, and vertically elongated ellipses, respectively. The direction difference from the other moving spots could affect the size of the apparent path. The speed had the most remarkable effect on the apparent paths. The perceptual vector analysis is applicable under slow speed conditions in the present experiments with a display of relatively large visual angle.This study was conducted in The Psychological Laboratory, Keio University in Yokohama     

Can test statistics in covariance structure analysis be trusted?

Covariance structure analysis uses chi 2 goodness-of-fit test statistics whose adequacy is not known. Scientific conclusions based on models may be distorted when researchers violate sample size, variate independence, and distributional assumptions. The behavior of 6 test statistics is evaluated with a Monte Carlo confirmatory factor analysis study. The tests performed dramatically differently under 7 distributional conditions at 6 sample sizes. Two normal-theory tests worked well under some conditions but completely broke down under other conditions. A test that permits homogeneous nonzero kurtoses performed variably. A test that permits heterogeneous marginal kurtoses performed better. A distribution-free test performed spectacularly badly in all conditions at all but the largest sample sizes. The Satorra-Bentler scaled test statistic performed best overall.     

Why does the base rate appear to be ignored? The equiprobability hypothesis

The base rate fallacy has been considered to result from people’s tendency to ignore the base rates given in tasks. In the present article, we note a particular, common structure of the tasks (the imbalanced probability structure) in which the fallacy is often observed. The equiprobability hypothesis explains the mechanism that produces the fallacy. This hypothesis predicts that task material that overrides people’s default equiprobability assumption can facilitate normative Bayesian inferences. The results of our two experiments strongly supported this prediction, and none of the alternative theories considered could explain the results. nt]mis|The present research was supported by Grant-in-Aid for Scientific Research 19500229 from the Japan Society for the Promotion of Science, awarded to M.H.     

NMDA receptor-dependent processes in the medial prefrontal cortex are important for acquisition and the early stage of consolidation during trace, but not delay eyeblink conditioning

Permanent lesions in the medial prefrontal cortex (mPFC) affect acquisition of conditioned responses (CRs) during trace eyeblink conditioning and retention of remotely acquired CRs. To clarify further roles of the mPFC in this type of learning, we investigated the participation of the mPFC in mnemonic processes both during and after daily conditioning using local microinfusion of the GABA(A) receptor agonist muscimol or the NMDA receptor antagonist APV into the rat mPFC. Muscimol infusions into the mPFC before daily conditioning significantly retarded CR acquisition and reduced CR expression if applied after sufficient learning. APV infusion also impaired acquisition of CRs, but not expression of well-learned CRs. When infusions were made immediately after daily conditioning, acquisition of the CR was partially impaired in both the muscimol and APV infusion groups. In contrast, rats that received muscimol infusions 3 h after daily conditioning exhibited improvement in their CR performance comparable to that of the control group. Both the pre- and post-conditioning infusion of muscimol had no effect on acquisition in the delay paradigm. These results suggest that the mPFC participates in both acquisition of a CR and the early stage of consolidation of memory in trace, but not delay eyeblink conditioning by NMDA receptor-mediated operations.     

Perceptual mechanism underlying gaze guidance in chimpanzees and humans

Previous studies comparing eye movements between humans and their closest relatives, chimpanzees, have revealed similarities and differences between the species in terms of where individuals fixate their gaze during free viewing of a naturalistic scene, including social stimuli (e.g. body and face). However, those results were somewhat confounded by the fact that gaze behavior is influenced by low-level stimulus properties (e.g., color and form) and by high-level processes such as social sensitivity and knowledge about the scene. Given the known perceptual and cognitive similarities between chimpanzees and humans, it is expected that such low-level effects do not play a critical role in explaining the high-level similarities and differences between the species. However, there is no quantitative evidence to support this assumption. To estimate the effect of local stimulus saliency on such eye-movement patterns, this study used a well-established bottom-up saliency model. In addition, to elucidate the cues that the viewers use to guide their gaze, we presented scenes in which we had manipulated various stimulus properties. As expected, the saliency model did not fully predict the fixation patterns actually observed in chimpanzees and humans. In addition, both species used multiple cues to fixate socially significant areas such as the face. There was no evidence suggesting any differences between chimpanzees and humans in their responses to low-level saliency. Therefore, this study found a substantial amount of similarity in the perceptual mechanisms underlying gaze guidance in chimpanzees and humans and thereby offers a foundation for direct comparisons between them.     

Modesty in self‐presentation: A comparison between the USA and Japan

Japanese participants in Study 1 exhibited a self‐effacing tendency when no reason for their self‐evaluation was provided. However, they exhibited a self‐enhancing tendency when they were offered a monetary reward for the correct evaluation. In Study 2, Americans, especially American men, exhibited a self‐enhancing tendency whereas Japanese exhibited a self‐effacing tendency when no reason for making the evaluation was presented. This cultural difference disappeared when participants were provided with a monetary reward for correctly evaluating their performance level. These results support the view that the modesty observed in self‐evaluation among Japanese participants is a ‘default strategy’ to avoid offending others.