Assuming too much from 'familiar' brain potentials

Familiarity is sometimes associated with midfrontal old/new (FN400) signals, but investigators assume too much by inferring familiarity whenever they identify these signals. We describe how Rosburg and colleagues (2011) made this assumption, yielding potentially faulty conclusions about the recognition heuristic. We provide an alternative interpretation emphasizing implicit processing that can underlie decision-making.     

Perception of size-related formant information in male koalas (Phascolarctos cinereus)

Advances in bioacoustics allow us to study the perceptual and functional relevance of individual acoustic parameters. Here, we use re-synthesised male koala bellows and a habituation-dishabituation paradigm to test the hypothesis that male koalas are sensitive to shifts in formant frequencies corresponding to the natural variation in body size between a large and small adult male. We found that males habituated to bellows, in which the formants had been shifted to simulate a large or small male displayed a significant increase in behavioural response (dishabituation) when they were presented with bellows simulating the alternate size variant. The rehabituation control, in which the behavioural response levels returned to that of the last playbacks of the habituation phase, indicates that this was not a chance increase in response levels. Our results provide clear evidence that male koalas perceive and attend to size-related formant information in their own species-specific vocalisations and suggest that formant perception is a widespread ability shared by marsupials and placental mammals, and perhaps by vertebrates more widely.     

Feedback-related brain activity predicts learning from feedback in multiple-choice testing

Different event-related potentials (ERPs) have been shown to correlate with learning from feedback in decision-making tasks and with learning in explicit memory tasks. In the present study, we investigated which ERPs predict learning from corrective feedback in a multiple-choice test, which combines elements from both paradigms. Participants worked through sets of multiple-choice items of a Swahili–German vocabulary task. Whereas the initial presentation of an item required the participants to guess the answer, corrective feedback could be used to learn the correct response. Initial analyses revealed that corrective feedback elicited components related to reinforcement learning (FRN), as well as to explicit memory processing (P300) and attention (early frontal positivity). However, only the P300 and early frontal positivity were positively correlated with successful learning from corrective feedback, whereas the FRN was even larger when learning failed. These results suggest that learning from corrective feedback crucially relies on explicit memory processing and attentional orienting to corrective feedback, rather than on reinforcement learning.     

Genetic moderation of sensitivity to positive and negative affect in marriage

Hypothesizing that genetic factors partially govern sensitivity to interpersonal cues, we examined whether a polymorphism (5-HTTLPR) in the serotonin transporter gene would moderate spouses' sensitivity to positive and negative partner affect. Before and after marital discussions, participants from 76 couples (total n = 150) reported their affective states. Spouses carrying the short allele of the 5-HTTLPR were more responsive to their partner's preinteraction positive affect and anxiety/nervousness, compared with spouses with two long alleles. These data support the contention that the serotonin system influences affective responses to social stimuli. In contrast to the view that the 5-HTTLPR primarily affects response to adverse experiences, these results suggest that this polymorphism moderates sensitivity to positive as well as negative affect.     

A quasi-experimental analysis of the influence of neighborhood disadvantage on child and adolescent conduct problems

A quasi-experimental comparison of cousins differentially exposed to levels of neighborhood disadvantage (ND) was used with extensive measured covariates to test the hypothesis that neighborhood risk has independent effects on youth conduct problems (CPs). Multilevel analyses were based on mother-rated ND and both mother-reported CPs across 4-13 years (n = 7,077) and youth-reported CPs across 10-13 years (n = 4,524) from the Children of the National Longitudinal Survey of Youth. ND was robustly related to CPs reported by both informants when controlling for both measured risk factors that are correlated with ND and unmeasured confounds. These findings are consistent with the hypothesis that ND has influence on conduct problems.     

Information theoretical approaches to chick-a-dee calls of Carolina chickadees (Poecile carolinensis)

One aim of this study was to apply information theoretical analyses to understanding the structural complexity of chick-a-dee calls of Carolina chickadees, Poecile carolinensis. A second aim of this study was to compare this structural complexity to that of the calls of black-capped chickadees, P. atricapillus, described in an earlier published report (Hailman, Ficken, & Ficken, 1985). Chick-a-dee calls were recorded from Carolina chickadees in a naturalistic observation study in eastern Tennessee. Calls were analyzed using approaches from information theory, including transition probability matrices, Zipf's rules, entropies, and information coding capacities of calls and notes of calls. As described for black-capped chickadees, calls of Carolina chickadees exhibited considerable structural complexity. Most results suggested that the call of Carolina chickadees is more structurally complex than that of black-capped chickadees. These findings add support to the growing literature on the complexity of this call system in Paridae species. Furthermore, these results point to the feasibility of detailed cross-species comparative analyses that may allow strong testing of hypotheses regarding signal evolution.     

Thin-slice perception develops slowly

Body language and facial gesture provide sufficient visual information to support high-level social inferences from "thin slices" of behavior. Given short movies of nonverbal behavior, adults make reliable judgments in a large number of tasks. Here we find that the high precision of adults' nonverbal social perception depends on the slow development, over childhood, of sensitivity to subtle visual cues. Children and adult participants watched short silent clips in which a target child played with Lego blocks either in the (off-screen) presence of an adult or alone. Participants judged whether the target was playing alone or not; that is, they detected the presence of a social interaction (from the behavior of one participant in that interaction). This task allowed us to compare performance across ages with the true answer. Children did not reach adult levels of performance on this task until 9 or 10 years of age, and we observed an interaction between age and video reversal. Adults and older children benefitted from the videos being played in temporal sequence, rather than reversed, suggesting that adults (but not young children) are sensitive to natural movement in social interactions.     

Attachment to objects as compensation for close others' perceived unreliability

Attachment theory posits that close interpersonal relationships provide people with psychological security across the lifespan. Research shows that when people perceive that close others are unreliable, they may seek alternative, non-social sources of security (e.g., deities). Building on this work, the authors hypothesized that attachment to objects compensates for threatened attachment security when close others are unreliable. Participants primed with close others', but not strangers', unreliability reported increased attachment to belongings (Study 1), and this effect was mediated by feelings of attachment anxiety (concern over close others' availability), but not attachment avoidance (avoiding emotional dependence; Study 2), suggesting that object attachment compensates for the perception that close others are unreliable rather than consistently rejecting. In Study 3, when a valued belonging was removed, participants primed with uncertainty about their relationships showed increased separation anxiety and motivation to reunite with the belonging, regardless of the belonging's perceived importance for facilitating relationships.