Does overall reinforcer rate affect discrimination of time‐based contingencies?

Overall reinforcer rate appears to affect choice. The mechanism for such an effect is uncertain, but may relate to reinforcer rate changing the discrimination of the relation between stimuli and reinforcers. We assessed whether a quantitative model based on a stimulus‐control approach could be used to account for the effects of overall reinforcer rate on choice under changing time‐based contingencies. On a two‐key concurrent schedule, the likely availability of a reinforcer reversed when a fixed time had elapsed since the last reinforcer, and the overall reinforcer rate was varied across conditions. Changes in the overall reinforcer rate produced a change in response bias, and some indication of a change in discrimination. These changes in bias and discrimination always occurred quickly, usually within the first session of a condition. The stimulus‐control approach provided an excellent account of the data, suggesting that changes in overall reinforcer rate affect choice because they alter the frequency of reinforcers obtained at different times, or in different stimulus contexts, and thus change the discriminated relation between stimuli and reinforcers. These findings support the notion that temporal and spatial discriminations can be understood in terms of discrimination of reinforcers across time and space.     

Escape from serial stimuli leading to food

If the functional relations governing the strength of a conditioned reinforcer correspond to those obtained with other Pavlovian procedures (e.g., Kaplan, 1984), the termination of stimuli appearing early in the interval between successive food deliveries should be reinforcing. During initial training we presented four key colors, followed by food, in a recurrent sequence to each of 6 pigeons. This established a baseline level of autoshaped pecking. In later sessions, we terminated each of these colors or only the first color for a brief period following each peck, replacing the original color with a standard substitute to avoid darkening the key. Pecking decreased in the presence of the last color in the sequence but increased in the presence of the first. In accord with contemporary models of Pavlovian conditioning, these and other data suggest that the behavioral effects of stimuli in a chain may be better understood in terms of what each stimulus predicts, as measured by relative time to the terminal reinforcer, than in the exclusively positive terms of the traditional formulation (Skinner, 1938). The same model may also account for the initial pause under fixed-interval and fixed-ratio schedules of reinforcement.     

父母低头行为对儿童青少年心理发展的影响

父母低头行为是指父母照顾或与孩子交流时,过分关注与使用手机而忽视孩子的行为。梳理相关研究发现,父母低头行为会对孩子产生多种不良影响,如,降低亲子关系交流质量、增加意外伤害风险、损伤人际交往能力、导致问题行为增多。现有研究采用取代假说、多任务操作理论以及依恋理论对影响过程进行解释。未来研究的关键在于邻近概念的区分、测量方式和研究方法的改进、探讨儿童对父母手机使用行为的看法以及移动设备对亲子互动可能的积极影响。     

SOME RELATIONS BETWEEN CLASSICALLY CONDITIONED AGGRESSION AND CONDITIONED SUPPRESSION IN SQUIRREL MONKEYS

During three experiments with squirrel monkeys, stimulus and shock pairings were given in the presence of a bite tube. Experiments 1 and 2 used a conditioned-suppression procedure in which bar pressing was reinforced with food. A transparent shield prevented biting of the bar. When the stimulus was paired with shock, bar pressing decreased (conditioned suppression) and tube biting increased during the stimulus (classically conditioned aggression). When the bite tube was removed on alternate sessions in Experiment 2, there was more suppression when the tube was present, thus suggesting that biting competed with bar pressing. However, this simple competing-response interpretation was complicated by the findings of Experiment 3 where, with naive monkeys, bar pressing was never reinforced with food, yet bar pressing was induced during the stimulus and was highest when the bite tube was absent. The fact that stimulus-induced bar pressing developed indicates that bar pressing in conditioned-suppression procedures, suppressed or not, may be maintained by two types of control—the food reinforcer and induced CS control. The higher rate of induced bar pressing during the stimulus with the bite tube absent confounds a simple competing response interpretation of conditioned suppression. It suggests that shock-induced responses during conditioned suppression could be both contributing to and competing with responding maintained by food, with the net effect depending on specific but ill-defined features of the situation.