Can't stop believing: inhibitory control and resistance to misleading testimony.

Why are some young children consistently willing to believe what they are told even when it conflicts with first-hand experience? In this study, we investigated the possibility that this deference reflects an inability to inhibit a prepotent response. Over the course of several trials, 2.5- to 3.5-year-olds (N = 58) heard an adult contradict their report of a simple event they had both witnessed, and children were asked to resolve this discrepancy. Those who repeatedly deferred to the adult's misleading testimony had more difficulty on an inhibitory control task involving spatial conflict than those who responded more skeptically. These results suggest that responding skeptically to testimony that conflicts with first-hand experience may be challenging for some young children because it requires inhibiting a normally appropriate bias to believe testimony.

Transient disruption of attentional performance following escalating amphetamine administration in rats.

RATIONALE: Attentional deficits are thought to be critically involved in the development of positive symptoms in schizophrenia. The present experiment tests the general hypothesis that sensitization of the mesolimbic dopaminergic system contributes to the attentional deficits in schizophrenia. OBJECTIVES: The present study assessed attentional performance following administration of an escalating amphetamine regimen and subsequent "challenge" amphetamine administration in rats. METHODS: Rats were trained to perform a two-lever sustained attention task that involved discrimination of visual signals and no signal presentation. After reaching criterion, subjects were assigned to receive escalating amphetamine or saline. Attentional performance was assessed immediately following escalating amphetamine, following "challenge" amphetamine administration (1.0 mg/kg) to amphetamine-pretreated rats, and for 3 days after the challenge session. At the end of this experiment, a dose-response study was conducted with saline-pretreated rats to confirm the appropriateness of the challenge dose. RESULTS: Amphetamine-pretreated animals demonstrated a transient increase in errors on nonsignal trials following escalating amphetamine administration. The latency to press a lever was decreased during and after challenge amphetamine administration. Administration of 1.0 mg/kg amphetamine did not alter accuracy of amphetamine-pretreated animals or of saline-pretreated animals in the dose-response experiment. CONCLUSIONS: Prior escalating amphetamine administration transiently disrupted attention, increasing incorrect "claims" for a signal on trials when no signal was presented. The present data support the existing literature that escalating amphetamine regimens may be useful to model the attentional deficits that contribute to the psychotic symptoms in schizophrenia.

Accuracy, confidence, and calibration: how young children and adults assess credibility.

Do children and adults use the same cues to judge whether someone is a reliable source of information? In 4 experiments, we investigated whether children (ages 5 and 6) and adults used information regarding accuracy, confidence, and calibration (i.e., how well an informant's confidence predicts the likelihood of being correct) to judge informants' credibility. We found that both children and adults used information about confidence and accuracy to judge credibility; however, only adults used information about informants' calibration. Adults discredited informants who exhibited poor calibration, but children did not. Requiring adult participants to complete a secondary task while evaluating informants' credibility impaired their ability to make use of calibration information. Thus, children and adults may differ in how they infer credibility because of the cognitive demands of using calibration.