Reinforcement by an imprinting stimulus versus water on simple schedules in ducklings

Ducklings (5 to 28 days old) were trained to peck a pole on fixed-ratio, fixed-interval, and multiple schedules using brief presentation of an imprinting stimulus as the response-contingent event. Other ducklings of the same age were trained similarly except that reinforcement consisted of access to water. With water reinforcement the typical fixed-ratio (“break-run”), fixed-interval (“scallop”), and multiple schedule response patterns were readily established and consistently maintained. With the imprinting stimulus these schedule effects were inconsistent in some subjects and virtually nonexistent in others, despite extended training. Schedule control with the imprinting stimulus was not improved by the use of a reinforcement signaling procedure which enhances responding reinforced by electrical brain stimulation on intermittent schedules. However, the overall rates of responding and the extinction functions generated after reinforcement with water versus the imprinting stimulus were comparable. These findings imply that control by temporal and discriminative stimuli may be relatively weak when a young organism's behavior is reinforced by presentation of an imprinting stimulus.     

General attentiveness effects of discriminative training

Using a design that permitted the simultaneous assessment of intra-, inter-, and extradimensional effects of discriminative training, the generality of discriminative effects that have been said to reflect increases in “general attentiveness” was assessed. Pigeons received either discriminative training with two stimuli correlated with reinforcement and one stimulus correlated with nonreinforcement, or nondifferential reinforcement (control) training. One positive stimulus was part of an intradimensional task and the other was not. After training, generalization tests were conducted to assess stimulus control along several dimensions. Discriminative training resulted in increased control along dimensions of the positive stimulus involved in the intradimensional task, but not along any dimensions of the other positive stimulus. The results suggested that discriminative training leads to increases in attention that are neither so general as suggested by the “general attentiveness” view nor so specific as to be revealed solely by intradimensional effects.     

Individual differences in judging deception: accuracy and bias

The authors report a meta-analysis of individual differences in detecting deception, confining attention to occasions when people judge strangers' veracity in real-time with no special aids. The authors have developed a statistical technique to correct nominal individual differences for differences introduced by random measurement error. Although researchers have suggested that people differ in the ability to detect lies, psychometric analyses of 247 samples reveal that these ability differences are minute. In terms of the percentage of lies detected, measurement-corrected standard deviations in judge ability are less than 1%. In accuracy, judges range no more widely than would be expected by chance, and the best judges are no more accurate than a stochastic mechanism would produce. When judging deception, people differ less in ability than in the inclination to regard others' statements as truthful. People also differ from one another as lie- and truth-tellers. They vary in the detectability of their lies. Moreover, some people are more credible than others whether lying or truth-telling. Results reveal that the outcome of a deception judgment depends more on the liar's credibility than any other individual difference.     

Can Deception by Salespersons and Customers Be Detected Through Nonverbal Behavioral Cues?1

Experiments on behavioral lie detection have indicated that observers can detect a communicator's lies with above-chance accuracy, and that detection accuracy may be enhanced when observers pay special attention to certain vocal and body-movement cues. The present experiment asked whether deception in (simulated) sales communications by retail salespersons and automobile customers could likewise be detected nonverbally. Contrary to much of the prior literature, deception-detection in this study was not above chance, apparently because the salespersons' and customers' nonverbal cues simply were not correlated with lying. Though the observers seemed quite suspicious and did not give communicators the “benefit of the doubt”, they could not discriminate the communicators' deceptive communications from their truthful ones. Many—perhaps most—of the lies in sales communications may be told by confident, well-practiced deceivers whose nonverbal behavior is unlikely to reveal their lying.