Reward and number of choices in children's probability learning: An attempt to reconcile conflicting findings

Five event schedules (75:0, 75:25, 75:0:0, 72:25:0, 75:12.5:12.5) were examined in a size discrimination task with penny rewards and plastic token markers. The subjects were 100 fourth graders (mean age = 9.4 years) and 100 undergraduates of both sexes. Whether or not the event probabilities summed to unity proved to be a more important determiner of terminal performance than the number of response alternatives in the task (p < .01). Females maximized more than males (p < .001) and college students more than fourth graders (p < .001). Greater maximization was exhibited by fourth graders in the reward condition (p < .01). These reward effects appeared to be more consistent with a detrimental-effects-of-reward interpretation than either utility or expectancy interpretations.     

Single-Stage Prediction Models Do Not Explain the Magnitude of Syntactic Disambiguation Difficulty

The disambiguation of a syntactically ambiguous sentence in favor of a less preferred parse can lead to slower reading at the disambiguation point. This phenomenon, referred to as a garden-path effect, has motivated models in which readers initially maintain only a subset of the possible parses of the sentence, and subsequently require time-consuming reanalysis to reconstruct a discarded parse. A more recent proposal argues that the garden-path effect can be reduced to surprisal arising in a fully parallel parser: words consistent with the initially dispreferred but ultimately correct parse are simply less predictable than those consistent with the incorrect parse. Since predictability has pervasive effects in reading far beyond garden-path sentences, this account, which dispenses with reanalysis mechanisms, is more parsimonious. Crucially, it predicts a linear effect of surprisal: the garden-path effect is expected to be proportional to the difference in word surprisal between the ultimately correct and ultimately incorrect interpretations. To test this prediction, we used recurrent neural network language models to estimate word-by-word surprisal for three temporarily ambiguous constructions. We then estimated the slowdown attributed to each bit of surprisal from human self-paced reading times, and used that quantity to predict syntactic disambiguation difficulty. Surprisal successfully predicted the existence of garden-path effects, but drastically underpredicted their magnitude, and failed to predict their relative severity across constructions. We conclude that a full explanation of syntactic disambiguation difficulty may require recovery mechanisms beyond predictability.     

Jewish-Arab violence: perspectives of a dominant majority and a subordinate minority

In 2 studies, the authors investigated intergroup violence as perceived by Israeli Jews and Israeli Arabs. University and junior high school students judged Jewish-Arab clashes, which ended in shots fired at a crowd of either Jewish or Arab demonstrators. The authors hypothesized that judgments of these shootings would be contingent on 3 variables: the origin of the respondent, the origin of the shooter, and the level of danger to the shooter. The results tended to support those hypotheses: (a) Both Jewish and Arab respondents justified shootings by members of their own group more readily than those by members of the other group. (b) Jewish judgments of violence were associated more closely than Arab judgments with the danger that the demonstrators posed to the shooter. (c) The Jewish respondents referred to self-defense more often than did the Arab respondents to justify their judgments, whereas the Arab respondents referred more often to intergroup considerations. Those differences may reflect the disagreement between the majority and the minority on the issue that each group should take into consideration in cases of international violence.     

On the relation between maternal state of mind and sensitivity in the prediction of infant attachment security

Attachment theorists assume that maternal mental representations influence responsivity, which influences infant attachment security. However, primary studies do not support this mediation model. The authors tested mediation using 2 mother-infant samples and found no evidence of mediation. Therefore, the authors explored sensitivity as a moderator, studying the (a) interaction of mental representation and sensitivity as it predicts infant attachment security and (b) level of sensitivity in mothers whose infants' attachment security is either concordant or discordant with their own. The interactional analyses were not significant. But the match-mismatch data showed that when mother-infant attachment strategies were discordant, maternal sensitivity was more consistent with infant than maternal attachment strategy. These findings are congruent with an interpretation of sensitivity as a moderator that can block transmission of attachment strategy.     

Prefrontal brain activity predicts temporally extended decision-making behavior

Although functional neuroimaging studies of human decision-making processes are increasingly common, most of the research in this area has relied on passive tasks that generate little individual variability. Relatively little attention has been paid to the ability of brain activity to predict overt behavior. Using functional magnetic resonance imaging (fMRI), we investigated the neural mechanisms underlying behavior during a dynamic decision task that required subjects to select smaller, short-term monetary payoffs in order to receive larger, long-term gains. The number of trials over which the longterm gains accrued was manipulated experimentally (2 versus 12). Event-related neural activity in right lateral prefrontal cortex, a region associated with high-level cognitive processing, selectively predicted choice behavior in both conditions, whereas insular cortex responded to fluctuations in amount of reward but did not predict choice behavior. These results demonstrate the utility of a functional neuroimaging approach in behavioral psychology, showing that (a) highly circumscribed brain regions are capable of predicting complex choice behavior, and (b) fMRI has the ability to dissociate the contributions of different neural mechanisms to particular behavioral tasks.