Neonatal imitation in chimpanzees (<Emphasis Type="Italic">Pan troglodytes</Emphasis>) tested with two paradigms

Primate species differ in their imitative performance, perhaps reflecting differences in imitative capacity. The developmentally earliest form of imitation in humans, neonatal imitation, occurs in early interactions with social partners, and may be a more accurate index of innate capacity than imitation of actions on objects, which requires more cognitive ability. This study assessed imitative capacity in five neonatal chimpanzees, within a narrow age range (7–15 days of age), by testing responses to facial and vocal actions with two different test paradigms (structured and communicative). Imitation of mouth opening was found in both paradigms. In the communicative paradigm, significant agreement was found between infant actions and demonstrations. Additionally, chimpanzees matched the sequence of three actions of the TC model, but only on the second demonstration. Newborn chimpanzees matched more modeled actions in the communicative test than in the structured paradigm. These performances of chimpanzees, at birth, are in agreement with the literature, supporting a conclusion that imitative capacity is not unique to the human species. Developmental histories must be more fully considered in the cross-species study of imitation, as there is a greater degree of innate imitative capacity than previously known. Socialization practices interact with innate and developing competencies to determine the outcome of imitation tests later in life.     

Trait Stability and Continuity in Childhood: Relating Sociability and Hostility to the Five-Factor Model of Personality

We investigated the continuity of personality constructs in the Oregon Youth Substance Use Project, a cohort-sequential study encompassing development from early childhood to adolescence with five annual or biennial assessments. Sociability and Hostility, assessed by teachers' ratings of children's behaviors at each assessment, were related to the traits comprising the Five-Factor model assessed by teachers' ratings at the fifth assessment. Confirmatory factor analysis demonstrated that Sociability and Hostility were reliably measured at each assessment, and these constructs were relatively stable over time (mean rank-order stability coefficients over intervals of 1-5 years were .50 and .43, respectively). Sociability was most strongly associated (positively) with Extraversion, and Hostility was most strongly associated (negatively) with Conscientiousness and Emotional Stability. No differences were found for younger versus older children. Implications for measuring childhood personality traits using teachers' reports of early childhood behavior are discussed.     

The Color-Vision Approach to Emotional Space: Cortical Evoked Potential Data

A framework for accounting for emotional phenomena proposed by Sokolov and Boucsein (2000) employs conceptual dimensions that parallel those of hue, brightness, and saturation in color vision. The approach that employs the concepts of emotional quality. intensity, and saturation has been supported by psychophysical emotional scaling data gathered from a few trained observers. We report cortical evoked potential data obtained during the change between different emotions expressed in schematic faces. Twenty-five subjects (13 male, 12 female) were presented with a positive, a negative, and a neutral computer-generated face with random interstimulus intervals in a within-subjects design, together with four meaningful and four meaningless control stimuli made up from the same elements. Frontal, central, parietal, and temporal ERPs were recorded from each hemisphere. Statistically significant outcomes in the P300 and N200 range support the potential fruitfulness of the proposed color-vision-model-based approach to human emotional space.     

The variance theory of the mirror effect in recognition memory

The mirror effect refers to a rather general empirical finding showing that, for two classes of stimuli, the class with the higher hit rates also has a lower false alarm rate. In this article, a parsimonious theory is proposed to account for the mirror effect regarding, specifically, high- and low-frequency items and the associated receiver-operating curves. The theory is implemented in a recurrent network in which one layer represents items and the other represents contexts. It is shown that the frequency mirror effect is found in this simple network if the decision is based on counting the number of active nodes in such a way that performance is optimal or near optimal. The optimal performance requires that the number of active nodes is low, only nodes active in the encoded representation are counted, the activation threshold is set between the old and the new distributions, and normalization is based on the variance of the input. Owing to the interference caused by encoding the to-be-recognized item in several preexperimental contexts, the variance of the input to the context layer is greater for highthan for low-frequency items, which yields lower hit rates and higher false alarm rates for high- than for low-frequency items. Although initially the theory was proposed to account for the mirror effect with respect to word frequency, subsequent simulations have shown that the theory also accounts for strength-based mirror effects within a list and between lists. In this case, consistent with experimental data, the variance theory suggests that focusing attention to the more difficult class within a list affects the hit rate, but not the false alarm rate and not the standard deviations of the underlying density, leading to no mirror effect.     

Electrophysiological evidence for the "missing link" in crossmodal attention.

Orienting attention involuntarily to the location of a sensory event influences responses to subsequent stimuli that appear in different modalities with one possible exception: orienting attention involuntarily to a sudden light sometimes fails to affect responses to subsequent sounds (e.g., Spence & Driver, 1997). Here we investigated the effects of involuntary attention to a brief flash on the processing of subsequent sounds in a design that eliminates stimulus-response compatibility effects and criterion shifts as confounding factors. In addition, the neural processes mediating crossmodal attention were studied by recording event-related brain potentials. Our data show that orienting attention to the location of a spatially nonpredictive visual cue modulates behavioural and neural responses to subsequent auditory targets when the stimulus onset asynchrony is short (between 100 and 300 ms). These findings are consistent with the hypothesis that involuntary shifts of attention are controlled by supramodal brain mechanisms rather than by modality-specific ones.     

Beyond the gambling paradigm: internal controllability in decision-making.

Much research within decision-making has used the standard gambling paradigm, where decision outcomes depend only on chance. Many real life decisions, however, imply personal control over decision outcomes. This paper addressed the question of how internal controllability influences decision-making. Internal controllability is assumed (i) to enhance unrealistic optimism and (ii) to result in a better cost:benefit ratio. Both tendencies support each other and predict an enhanced attractiveness for internal and controllable choice options. Participants read a scenario and made a decision afterwards. Results supported the prediction: decision-makers take the option they can personally control. This finding widens the narrow perspective inherent in much previous research based on the gambling paradigm.