Interactions in multiple schedules: negative induction with squirrel monkeys

In Experiment I, lever pressing by squirrel monkeys was maintained under a sequence of variable-interval, multiple variable-interval variable-interval, and multiple variable-interval extinction schedules of food presentation. Negative induction (decreased responding in the unchanged component) occurred when one component of the multiple variable-interval variable-interval schedule was changed to extinction. Negative induction was transient over sessions; responding in the unchanged component usually recovered to a rate similar to that under the multiple variable-interval variable-interval schedule. Negative induction was not accompanied by consistent changes in the patterns of local responding within the unchanged component, and did not depend on whether component schedules were associated with localized (lever lights) or diffuse visual stimuli (houselights), or on whether the unchanged component was a 60- or 180-sec variable-interval schedule. In Experiment II, responding was maintained under a sequence of variable-interval and multiple variable-interval timeout schedules of food presentation. Negative induction occurred when responding declined gradually in the timeout component but not when responding declined abruptly. The nature of interactions in multiple schedules may depend on the species; negative induction was observed with squirrel monkeys under conditions similar to those that produce positive contrast with pigeons.     

The interaction between schizotypy and latent inhibition: modulation by experimental parameters

Two recent experiments (Della Casa et al., in press) yielded the typical reduced latent inhibition (LI) in high vs low schizotypy subjects after a slow, irregularly presented masking task (Stroop task), and reduced LI in low vs high schizotypy subjects after a fast, regularly presented masking task. The present experiment was aimed at testing whether speed or regularity was responsible for the different results. The present slow, regular experiment replicated the results of the former slow, irregular experiment, i.e. reduced LI in high schizotypals and significant LI in low schizotypals, indicating that speed and not regularity is the critical experimental variable. The modulation of the schizotypy—latent inhibition relationship can be attributed to differences in attentional resources or the time available to process the to-be-target stimuli during preexposure, in accordance with the hypothesis of Lubow and Gewirtz, 1995 that automatic processing of these stimuli is critical for the development of latent inhibition in adult humans. In addition, results on Stroop and negative priming effects are presented.     

Variable-interval schedules of timeout from avoidance

Rats were trained on concurrent schedules in which pressing one lever postponed shock and pressing the other occasionally produced a 2-min timeout during which the shock-postponement schedule was suspended and its correlated stimuli were removed. Throughout, the shock-postponement schedule maintained proficient levels of avoidance. Nevertheless, in Experiment 1 responding on the timeout lever was established rapidly, was maintained at stable levels on variable-interval schedules, was extinguished by withholding timeout, was reestablished when timeout was reintroduced, and was brought under discriminative control with a multiple variable-interval extinction schedule of timeout. These results are in contrast with Verhave's (1962) conclusion that timeout is an ineffective reinforcer when presented to rats on intermittent schedules. In Experiment 2 the consequence of responding on the timeout lever was altered so that the shock-postponement schedule remained in effect even though the stimulus conditions associated with timeout were produced for 2 min. Responding extinguished, indicating that suspension of the shock-postponement schedule, not stimulus change, was the source of reinforcement. By establishing the reinforcing efficacy of timeout with standard variable-interval schedules, these experiments illustrate a procedure for studying negative reinforcement in the same way as positive reinforcement.     

REDUCING SELF-INJURY AND CORRESPONDING SELF-RESTRAINT THROUGH THE STRATEGIC USE OF PROTECTIVE CLOTHING

We examined the use of protective clothing to reduce a retarded male's face-punching and leg-kicking and two corresponding forms of self-restraint—arm and leg self-restraint. The resident was observed each day in three sessions of randomly ordered conditions (one condition per session): without any protective clothing, with a padded helmet, and with a padded helmet and padded slippers. Use of the padded helmet substantially reduced face-punching and arm self-restraint. The addition of padded slippers reduced leg-kicking and leg self-restraint. These results suggest a practical and effective means of controlling self-injury and self-restraint. They are also consistent with the possibility that the resident's arm restraint was maintained in part by escape or avoidance of face-punching and that his leg restraint was maintained in part by escape or avoidance of leg-kicking.     

The effects of cocaine on behavior maintained by timeout from avoidance.

Rats were trained on concurrent schedules under which responses on one lever postponed shock (avoidance) and responses on the other lever produced brief (2-min) periods of signaled timeout from avoidance. For 6 rats, timeout from avoidance was programmed on a variable-interval 45-s schedule that generally resulted in rates that were lower than those on the avoidance lever. For another 6 rats, timeout was arranged on a variable-ratio 15 schedule that produced higher baseline rates. Cocaine (3 to 40 mg/kg) produced large, dose-dependent increases in behavior maintained by timeout in both groups of rats. Avoidance responding was also generally increased by cocaine, but the increases were of lesser magnitude. Increases in response rates were seen across a broad range of doses on behavior maintained by either interval or ratio schedules, an outcome that was unexpected on the basis of most studies of cocaine on food-maintained behavior. These results were similar to those of previous studies of the effects of amphetamine on behavior maintained by timeout from avoidance and suggest that stimulant drugs affect behavior maintained under a shock-postponement schedule differently than they affect behavior maintained by timeout from avoidance.     

The unification of mind: Integration of hemispheric semantic processing

Seventy-six participants performed a visual half-field lexical decision task at two different stimulus onset asynchronies (50 or 750 ms). Word targets were primed either by a highly associated word (e.g., CLEAN-DIRTY), a weakly associated word (e.g., CLEAN-TIDY), or an unrelated word (e.g., CLEAN-FAMILY) projected to either the same or opposite visual field (VF) as the target. In the short SOA, RVF-left hemisphere primes resulted in high associate priming regardless of target location (ipsilateral or contralateral to the prime) whereas LVF-right hemisphere primes produced both high and low associate priming across both target location conditions. In the long SOA condition, contralateral priming patterns converged, demonstrating only high associate priming in both VF locations. The results of this study demonstrate the critical role of interhemispheric transfer in semantic processing and indicate a need to elaborate current models of semantic processing.     

IAT效应在不同目标概念水平上的差异研究

采用IAT实验设计,考察大学生对不同概念词的内隐态度之间的差别。结果发现,八组实验材料都产生了显著的IAT效应;不同性别的测验材料的IAT效应间不存在显著差异,不同喜好程度的测验材料的IAT效应间存在显著差异,且两个因素存在显著的交互作用。研究表明,IAT效应既可在上位概念水平上产生,亦可在下位概念水平上产生。     

选择性注意加工机制上学困生和学优生的比较研究

本实验使用正、负启动技术 ,在严格控制各种条件下比较学困生和学优生在选择性注意加工机制———目标激活和分心物抑制方面的差异 ,进而探讨学困生在选择性注意加工机制上所存在的问题。结果显示 ,学困生和学优生的正启动量差异不显著 (p >0 .0 5 ) ,但学困生的负启动量显著小于学优生 (p <0 .0 0 1。这一结果说明 ,学困生在对目标反应期间易受分心物干扰 ,其抑制分心物干扰的能力较弱。同时启示我们应注重训练学困生抑制分心物干扰的能力     

Effects of violent movies and trait hostility on hostile feelings and aggressive thoughts

The General Affective Aggression Model [Anderson CA, Deuser WE, DeNeve KM (1995): Personality and Social Psychology Bulletin 21:434–448; Anderson CA, Anderson KB, Deuser WE (1996): Personality and Social Psychology Bulletin 22:366–376] suggests that violent movies may increase aggression by increasing hostile feelings and the accessibility of aggressive thoughts. It also suggests that trait hostility may similarly influence affect and cognition. Experiment 1 explored the effects of viewing violent movie clips on affect and cognition. Participants who viewed a violent movie clip later reported higher levels of state hostility than did those who viewed a nonviolent clip. Experiment 2 added trait hostility to the design as a potentially important individual difference variable. The state hostility results of Experiment 1 were replicated. In addition, the relative accessibility of aggressive thoughts was increased by the violent clip, but only for low irritable participants. Discussion focused on the relevance to aggressive behavior. Aggr. Behav. 23:161–178, 1997. © 1997 Wiley-Liss, Inc.