Error discounting in probabilistic category learning

The assumption in some current theories of probabilistic categorization is that people gradually attenuate their learning in response to unavoidable error. However, existing evidence for this error discounting is sparse and open to alternative interpretations. We report 2 probabilistic-categorization experiments in which we investigated error discounting by shifting feedback probabilities to new values after different amounts of training. In both experiments, responding gradually became less responsive to errors, and learning was slowed for some time after the feedback shift. Both results were indicative of error discounting. Quantitative modeling of the data revealed that adding a mechanism for error discounting significantly improved the fits of an exemplar-based and a rule-based associative learning model, as well as of a recency-based model of categorization. We conclude that error discounting is an important component of probabilistic learning.     

The effects of relationship context and modality on ratings of funniness

There is evidence to suggest that humour is an important part of mate choice and that humour may serve as an indicator of genetic quality. The current study investigated how rated funniness from a video clip was related to an individual’s attractiveness as a short-term or long-term partner. We additionally tested for the presence of an attractiveness halo effect on humour ratings by comparing ratings of funniness from video clips, audio-only presentations, and photographs. We found that funniness was most strongly correlated with attractiveness for short-term relationships, especially in videos of males. We also found that attractiveness was related to funniness ratings differently across video, audio-only clips, and photographs. Relative to their rated funniness in the audio-only condition, with no appearance cues, attractive individuals were rated as funnier in video clips than less attractive individuals. An additional study demonstrated that ratings of flirtatiousness and funniness were strongly correlated. Perceived similarity between producing humour and flirting may explain why humour is more preferable in a short-term partner as flirting may be seen to signal proceptivity. The effects of attractiveness on humour judgement may also be explained by an association with flirtation as flirting may be most enjoyable when directed by attractive individuals.     

Using Principal Components as Auxiliary Variables in Missing Data Estimation

To deal with missing data that arise due to participant nonresponse or attrition, methodologists have recommended an “inclusive” strategy where a large set of auxiliary variables are used to inform the missing data process. In practice, the set of possible auxiliary variables is often too large. We propose using principal components analysis (PCA) to reduce the number of possible auxiliary variables to a manageable number. A series of Monte Carlo simulations compared the performance of the inclusive strategy with eight auxiliary variables (inclusive approach) to the PCA strategy using just one principal component derived from the eight original variables (PCA approach). We examined the influence of four independent variables: magnitude of correlations, rate of missing data, missing data mechanism, and sample size on parameter bias, root mean squared error, and confidence interval coverage. Results indicate that the PCA approach results in unbiased parameter estimates and potentially more accuracy than the inclusive approach. We conclude that using the PCA strategy to reduce the number of auxiliary variables is an effective and practical way to reap the benefits of the inclusive strategy in the presence of many possible auxiliary variables.     

Professors are people too: The impact of informal evaluations of professors on students and professors

There are websites where individuals anonymously provide informal reviews of professors. What impact do such sites have on student and professor motivational factors? Research suggests that undergraduate students are affected (e.g. Edwards et?al. in J Comput Mediat Commun 14:368?C392, 2009; Kowai-Bell et?al. in Comput Hum Behav 27(5):1862?C1867, 2011). The goals of the present investigation are to (1) see if Master??s level students are also influenced and (2) investigate how professors are affected. We provided students (Study 1) and professors (Study 2) comments from an informal review website and they, respectively, took the perspective of a potential student or the professor described in the comments. In Study 1, consistent with prior research on undergraduates, Master??s level students were affected by the reviews (perceived control, outcome expectancies, affect toward taking the class, and likelihood of recommending to a friend), in accordance with the valence of the reviews. Among professors (Study 2), the valence of the reviews influenced affect and self-concept with respect to relational aspects of teaching (mood, affect toward teaching again, confidence that students liked them, and confidence that they would have rapport with future students) but did not have an effect on professor self-concept with respect to competence (teaching ability and teaching well in the future). Furthermore, preliminary evidence suggests that new professors are more susceptible than experienced professors. The results of these studies are relevant because of the degree to which students and instructors contribute to the socioemotional climate of the classroom (Frenzel et?al. in J Educ Psychol 103(3):705?C716, 2009; Radel et?al. in J Educ Psychol 102(3):577?C587, 2010).     

Dana-Farber Cancer Institute ethics rounds: life-threatening illness and the desire to adopt

Originally presented during Ethics Rounds at the Dana-Farber Cancer Institute, this commentary on the case of a patient treated for life-threatening cancer explores the responsibilities of health care providers when addressing the patient's desire to adopt a child.     

Aggression and self-esteem: a diary study of children's reactivity to negative interpersonal events

The study employs a daily diary design to assess self-esteem reactivity and its association with children's aggressive behavior. We test the hypothesis that the self-esteem of aggressive children will be more reactive to negative interpersonal events than the self-esteem of nonaggressive children. Results provide partial support for the aggression/reactivity hypothesis. Aggressive children's self-esteem was more reactive to negative peer events but less reactive to negative adult events than the self-esteem of less aggressive children. These findings are discussed in relation to the experimental literature relating self-esteem instability and ego-threat to aggression and in relation to the extensive body of research on childhood aggression. Intervention implications are also considered.     

Category contingent aftereffects for faces of different races, ages and species

Exposure to faces biases perceptions of subsequently viewed faces such that normality judgments of similar faces are increased. Simultaneously inducing such an aftereffect in opposite directions for two groups of faces might indicate discrete responding of the neural populations coding for those groups. Here we show such "category contingent" aftereffects following exposure to faces differing in eye-spacing (wide versus narrow) for European versus African faces, adult versus infant faces, and human versus monkey faces. As aftereffects reflect changes in responses of neural populations that code faces, our results may then suggest that functionally distinct neural populations code faces of different ages, races and species and that the human brain potentially contains discrete representations of these categories.     

Event-related fMRI of category learning: differences in classification and feedback networks

Eighteen healthy young adults underwent event-related (ER) functional magnetic resonance imaging (fMRI) of the brain while performing a visual category learning task. The specific category learning task required subjects to extract the rules that guide classification of quasi-random patterns of dots into categories. Following each classification choice, visual feedback was presented. The average hemodynamic response was calculated across the eighteen subjects to identify the separate networks associated with both classification and feedback. Random-effects analyses identified the different networks implicated during the classification and feedback phases of each trial. The regions included prefrontal cortex, frontal eye fields, supplementary motor and eye fields, thalamus, caudate, superior and inferior parietal lobules, and areas within visual cortex. The differences between classification and feedback were identified as (i) overall higher volumes and signal intensities during classification as compared to feedback, (ii) involvement of the thalamus and superior parietal regions during the classification phase of each trial, and (iii) differential involvement of the caudate head during feedback. The effects of learning were then evaluated for both classification and feedback. Early in learning, subjects showed increased activation in the hippocampal regions during classification and activation in the heads of the caudate nuclei during the corresponding feedback phases. The findings suggest that early stages of prototype-distortion learning are characterized by networks previously associated with strategies of explicit memory and hypothesis testing. However as learning progresses the networks change. This finding suggests that the cognitive strategies also change during prototype-distortion learning.