The physical properties of bar-pressing behaviour and the problem of reactive inhibition

Many of the terms used in the literature on reactive inhibition are vague, subjective or incorrect. The weighted bar is not a suitable device in the study of this problem, since it records irrelevant aspects of behaviour. An experiment using apparatus which gives a continuous record of the force which a rat applies to a knob produces the following results. After much practice, pressing becomes sharp and brief and the amount of activity per reward is reduced. Under conditions of no (intentional) secondary reward the amount of activity during extinction is at first positively correlated with the average activity per reward during training, but the correlation diminishes as extinction proceeds. With auditory secondary reward there is no correlation.     

Conditioned suppression of bar-pressing behavior by stimuli associated with drugs

Ten naive male albino rats were trained to press a bar under a variable-interval 30-sec schedule with water as the reinforcer in two experiments. This behavior was disrupted by chlorpromazine in Experiment I (two rats) and by lysergic acid diethylamide (LSD) in both Experiment I (two rats) and Experiment II (six rats). The administration of the drug was paired with an originally neutral white light. After several pairings with either drug, the light also depressed behavior. When the light was no longer paired with drug, the depression effect extinguished much faster than is usually observed in conditioned suppression studies.     

The timing of meals

In most individuals, food intake occurs as discrete bouts or meals, and little attention has been paid to the factors that normally determine when meals will occur when food is freely available. On the basis of experiments using rats, the authors suggest that when there are no constraints on obtaining food and few competing activities, 3 levels of interacting controls normally dictate when meals will start. The first is the genetically determined circadian activity pattern on which nocturnal animals tend to initiate most meals in the dark. The second is the regularly occurring changing of the light cycle: These changes provide temporal anchors. The third relates to the size of the preceding meal, such that larger meals cause a longer delay until the onset of the next meal. Superimposed on these 3 are factors related to learning, convenience, and opportunity.     

The timing of appraisals

The appraisal process consists of the subjective evaluation that occurs during an individual's encounter with significant events in the environment, determining the nature of the emotional reaction and experience. Placed in the context of appraisal theories of emotion-elicitation and differentiation, the aim of the present research was to test empirically the hypothesis that the intrinsic pleasantness evaluation occurs before the goal conduciveness evaluation. In two studies, intrinsically pleasant and unpleasant images were used to manipulate pleasantness, and a specific event in a Pacman-type videogame was used to manipulate goal conduciveness. Facial EMG was used to measure facial reactions to each evaluation. As predicted, facial reactions to the intrinsic pleasantness manipulation were faster than facial reactions to the goal conduciveness manipulation. These results provide good empirical support for the sequential nature of the appraisal process.     

The relationship between quantity,type, and timing of external childcare and child problem behaviour in Switzerland

This study aimed to investigate the relationship between external childcare and child problem behaviour at age 7 in a culturally diverse urban sample from Switzerland. We used data from the Zurich Project on the Social Development of Children and Youths (z-proso). Findings suggested that the quantity of group-based childcare (but not individual childcare) was related to aggression, ADHD, non-aggressive externalizing behaviour, and anxiety and depression at age 7. Analyses on timing of childcare suggested that the accumulation of childcare over the life course, and not so much childcare in the first years of life, was associated with child problem behaviour. In addition, childcare at age 5 to 7 had a unique relationship with problem behaviour over and above quantity of group-based childcare received in other age periods.     

Effect of effort on resistance to extinction of the bar-pressing response

This study was designed to obtain more information on the relation between effort and resistance to extinction when all subjects receive equal acquisition experience on each effort level at which the response is subsequently to be extinguished. Twenty-four subjects were given 120 reinforcements on each of three weighted bars of 5, 40 and 70 gm. They were then ordered into three groups, each extinguished on one effort level. Analysis of the number of responses emitted in six daily 20-min. extinction sessions showed that resistance to extinction was not related to the amount of effort expended in extinction.     

The timing of interresponse intervals

Analogs of models of duration discrimination are here related to the timing of discrete motor responses. The measure of interest is the variability in duration of intervals collected in short interval reproduction tasks. For data from a Morse key-tapping task, it is shown that, taken separately, neither of the models described can completely account for the relation between the mean and the variance of the interresponse intervals.