Reinforcement magnitude and pausing on progressive-ratio schedules

Rats responded under progressive-ratio schedules for sweetened milk reinforcers; each session ended when responding ceased for 10 min. Experiment 1 varied the concentration of milk and the duration of postreinforcement timeouts. Postreinforcement pausing increased as a positively accelerated function of the size of the ratio, and the rate of increase was reduced as a function of concentration and by timeouts of 10 s or longer. Experiment 2 varied reinforcement magnitude within sessions (number of dipper operations per reinforcer) in conjunction with stimuli correlated with the upcoming magnitude. In the absence of discriminative stimuli, pausing was longer following a large reinforcer than following a small one. Pauses were reduced by a stimulus signaling a large upcoming reinforcer, particularly at the highest ratios, and the animals tended to quit responding when the past reinforcer was large and the stimulus signaled that the next one would be small. Results of both experiments revealed parallels between responding under progressive-ratio schedules and other schedules containing ratio contingencies. Relationships between pausing and magnitude suggest that ratio pausing is under the joint control of inhibitory properties of the past reinforcer and excitatory properties of stimuli correlated with the upcoming reinforcer, rather than under the exclusive control of either factor alone.     

Effects of indoor lighting (illuminance and spectral distribution) on the performance of cognitive tasks and interpersonal behaviors: The potential mediating role of positive affect

Three studies examined the effects of key aspects of indoor lighting (illuminance, spectral distribution) on the performance of tasks that did not primarily involve visual processing. It was hypothesized that lighting conditions which generated positive affect among subjects would influence behavior and cognition in ways consistent with the findings of previous research on the influence of such affect. Results of all three studies offered partial support for this hypothesis. In Study 1, male and female subjects exposed to relatively low levels of illuminance (150 lux) assigned higher performance appraisals to a fictitious employee and included a broader range of words in specific word categories than subjects exposed to relatively high levels of illuminance (1500 lux). In Study 2, subjects exposed to warm white light reported stronger preferences for resolving interpersonal conflicts through collaboration and weaker preferences for resolving conflicts through avoidance than subjects exposed to cool-white light. Additionally, illuminance and spectral distribution (color) interacted to influence subjects' self-set goals on a clerical coding task. In Study 3, receipt of a small, unexpected gift and exposure to warm-white light both increased the amount of time subjects were willing to donate as unpaid volunteers. In addition, in the absence of a gift, subjects volunteered more time under low than under high illuminance.This research was supported by funds from the Niagaru Mohawk Energy-Efficient Seed Research program and from the New York State Energy Research and Development Authority. Study 1 was conducted by Susan G. Daniels in partial fulfillment of requirements for the Master of Science degree. The authors wish to express their sincere appreciation to Marna Bronfen and Jill Thomley for their aid in collection of the data for Studies 2 and 3 and in statistical analyses. Thanks are also due to Sylvania, Inc., for supplying lamps, and to Bob Davis and Peter Boyce for their invaluable assistance in several respects.     

Fear,attachment and affiliation: The interaction of functional systems in 8- and 12-month-old infants

In this research fear of strangers has been analysed as it interacts with attachment and affiliation, and in relation to developmental level, in conditions most similar to the natural situations where encounters with unfamiliar persons take place. A total of 30 infants and their mothers participated. The children were divided into two groups (8-9 and 11-12 months). Each infant was approached by two females, who, in turn, produced either of two natural sequences. Our results allowed us to confirm the universality of fear and its coexistence and interaction with attachment and affiliation. As far as the role that developmental level plays, it was noted that in the 12-month-old infants fear reactions were more intense than in the younger ones. Furthermore, the attachment system was more activated in the older group in the intrusive episodes, but when the threatening nature of the situation decreased, attachment was activated less in the 12-month-old group. Another difference was related to control resources. While in the younger infants we observed a tendency to control their own emotional state, the 12-month-old infants tried to gain control over the stranger. These results were interpreted by considering the adaptative value of an increase with age of the capacity to evaluate a situation's threat value, of attachment security, and of behavioural resources permitting some control over the stranger's behaviour.     

Recognition memory in older adults: adjustment to changing contingencies.

Four older and 4 younger men were given extended exposure to a continuous-recognition memory procedure. Experimental variables included the type of stimulus (alphanumeric strings, words, or sentences), the intervals separating repeated items, gains and losses for correct and incorrect recognitions, and the extent of practice with the memory task. Signal detection analyses indicated that the older men generally were less accurate (sensitivity), particularly when the stimuli were strings, but that age differences decreased with practice. Under conditions in which the payoff matrix was neutral, the older and younger men showed equivalent rates of hits and false alarms (bias). Alteration of the matrix to require more liberal or more conservative patterns of recognition responding led to corresponding changes for men of both ages. Adjustments by the older men, however, were not as close to the bias values called for by the new matrices.     

Social Costs of Smoking: Effects of Tobacco Smoke on Hostile Behavior1

Male and female undergraduates interacted with a same-sex experimenter and a same-sex assistant of the experimenter. Either the experimenter or the assistant smoked. Subjects were provoked or not provoked by the experimenter and then smoked. Subjects were provoked or not provided by the experimenter and then provided with an opportunity to treat him or her in a hostile manner. Additionally, subjects were classified as smokers or nonsmokers and as supporting or opposing smoking in public places. Tobacco smoke was found to facilitate hostile behavior whether or not subjects were independently annoyed and whether or not it originated from the annoyer or a bystander. No sex differences were observed in this effect. Also, no appreciable difference was observed in the hostile behavior of smokers and nonsmokers. Persons opposed to public smoking reacted more strongly to the provocation than persons supportive of public smoking, but this effect was independent of the presence or absence of smoke.     

The informativeness and frequency of presentation of a social stimulus as determinants of its efficacy as a reinforcer

It was demonstrated that variations in the informativeness of a social stimulus place important limitations on the generality of the proposition that deprivation heightens, while satiation lowers, responsiveness to a social stimulus. Using 60 children 5 to 6 years of age as subjects, a social stimulus (“good”) was presented at either a high or a low frequency in one of three information-value contexts (high, medium, or low). Immediately following the exposure treatment the same social stimulus was employed as a reinforcer of nonpreferred responses in a two-choice discrimination learning task. The findings indicated that the heightened efficacy of deprivation relative to satiation only held for low information value; when initial information value was high the subsequent efficacy of a social stimulus was enhanced by its initial recurrent usage. Trend analyses revealed that the effects of variations in information value were strongest within the high-frequency-of-praise treatment. Possible mechanisms underlying the significant Information Value × Frequency interaction were discussed.