Visual variability affects early verb learning

Research demonstrates that within‐category visual variability facilitates noun learning; however, the effect of visual variability on verb learning is unknown. We habituated 24‐month‐old children to a novel verb paired with an animated star‐shaped actor. Across multiple trials, children saw either a single action from an action category (identical actions condition, for example, travelling while repeatedly changing into a circle shape) or multiple actions from that action category (variable actions condition, for example, travelling while changing into a circle shape, then a square shape, then a triangle shape). Four test trials followed habituation. One paired the habituated verb with a new action from the habituated category (e.g., ‘dacking’ + pentagon shape) and one with a completely novel action (e.g., ‘dacking’ + leg movement). The others paired a new verb with a new same‐category action (e.g., ‘keefing’ + pentagon shape), or a completely novel category action (e.g., ‘keefing’ + leg movement). Although all children discriminated novel verb/action pairs, children in the identical actions condition discriminated trials that included the completely novel verb, while children in the variable actions condition discriminated the out‐of‐category action. These data suggest that – as in noun learning – visual variability affects verb learning and children's ability to form action categories.     

Categorization of Prototypical Stimulus Classes by Pigeons

Previous findings have demonstrated the pigeon's ability to categorize sets of schematic faces defined by a polymorphous feature rule. We present here an experiment that was conducted to evaluate the influence of the category structure determined by the distribution of features across stimulus classes. The task was a middle-value discrimination, involving a band of positive stimuli surrounded by a band of negative stimuli. Two large sets of Brunswik faces were conceptualized as variations of a standard stimulus (prototype) and occupied highly overlapping regions in the feature space. The classes could be separated in terms of a distance-from-prototype rule. Only three of five animals were successful in classification training. Analyses of both the transfer performance and of the effects of feature values on the variance of responding revealed the classical prototype effect-that is, performance determined by the overall similarity to the central tendency of the classes. A theoretical evaluation of the data examines the possibility that pigeons discriminated between the classes by virtue of a prototype-distance rule, although exemplar models offer more parsimonious accounts.     

Effects of Cognitive Complexity and Emotional Upset on Processing Supportive Messages: Two Tests of a Dual‐Process Theory of Supportive Communication Outcomes

We report tests of hypotheses derived from a theory of supportive communication outcomes that maintains the effects of supportive messages are moderated by factors influencing the motivation and ability to process these messages. Participants in two studies completed a measure of cognitive complexity, which provided an assessment of processing ability, and reported their degree of upset with a problem situation, which was hypothesized to impact both motivation and ability; they subsequently evaluated the helpfulness of comforting messages that varied in person centeredness. Consistent with predictions, an index of message processing depth—the degree to which participants discriminated between the helpfulness of better and worse supportive messages—was associated with the factors additively in both studies and interactively in one study.     

L-type voltage-gated calcium channels in conditioned fear: a genetic and pharmacological analysis

Using pharmacological approaches, others have suggested that L-type voltage-gated calcium channels (L-VGCCs) mediate both consolidation and extinction of conditioned fear. In the absence of L-VGCC isoform-specific antagonists, we have begun to investigate the subtype-specific role of LVGCCs in consolidation and extinction of conditioned fear using a molecular genetics approach. Previously, we used this approach to demonstrate that the Ca(v)1.3 isoform mediates consolidation, but not extinction, of contextually conditioned fear. Here, we used mice in which the gene for the L-VGCC pore-forming subunit Ca(v)1.2 was conditionally deleted in forebrain excitatory neurons (Ca(v)1.2(cKO) mice) to address the role of Ca(v)1.2 in consolidation and extinction of conditioned fear. We demonstrate that Ca(v)1.2(cKO) mice consolidate and extinguish conditioned fear as well as control littermates. These data suggest that Ca(v)1.2 is not critical for these processes and together with our previous data argue against a role for either of the brain-expressed L-VGCCs (Ca(v)1.2 or Ca(v)1.3) in extinction of conditioned fear. Additionally, we present data demonstrating that the L-VGCC antagonist nifedipine, which has been used in previous conditioned fear extinction studies, impairs locomotion, and induces an aversive state. We further demonstrate that this aversive state can enter into associations with conditioned stimuli that are present at the time that it is experienced, suggesting that previous studies using nifedipine were likely confounded by drug toxicity. Taken together, our genetic and pharmacological data argue against a role for Ca(v)1.2 in consolidation of conditioned fear as well as a role for L-VGCCs in extinction of conditioned fear.