The effects of response-reinforcer contingency on time allocation in the open field

The present experiment explores the effects of the response (1-sec occupancy of a target area in an open field)—reinforcer (intracranial stimulation) contingency on time allocation in the open field in rats. The probability of reinforcement given a response (X) and the probability of reinforcement given the absence of a response (Y) were varied randomly across sessions within a subject. The following (X, Y) values were utilized: (.05, 0), (.15, 0), (.25, 0), (.15, .05), and (.15, .15). The results of this experiment indicate that rate of acquisition of time allocation preference is uniformly rapid during all contingency treatments wherein Y = 0 and is negatively related to the value of Y when X = .15. The relationship between the asymptote of the time allocation acquisition function and the value of X (when Y = 0) is positively sloped and negatively accelerated, while the relationship between asymptote and the value of Y (when X = .15) is negatively sloped with zero acceleration. Proposed contingency metrics are evaluated.     

Stimulus generalization of auto-shaped key-pecking following interdimensional and extradimensional training

In three experiments, groups of pigeons were tested for wavelength generalization of auto-shaped key-pecking following different types of training. In Experiment I, one group received auto-shape trials with a 555-nm CS. Another group received auto-shape trials with a 555-nm CS and a white CS. A third group received auto-shape trials with a 555-nm CS and a white CS, except the white CS was nonreinforced. The third group yielded the sharpest gradient, whereas the second group yielded the flattest gradient. In Experiment II, one group received auto-shape trials with a 555-nm CS. A second group received auto-shape trials with a 555-nm CS and a compound CS consisting of a vertical white line on a 555-nm background. A third group received auto-shape trials with a 555-nm CS and a compound CS, except that the compound was nonreinforced. The third group yielded the sharpest wavelength gradient, whereas the second group yielded the flattest. In Experiment III, exposure differences to 555 nm in Experiment II resulting from differential speeds of auto-shape acquisition were controlled by the use of an ITI manipulation. Amount of exposure to 555 nm was shown not to be responsible for the results of Experiment II.     

Correlations between rats' spatial location and intracranial stimulation administration affects rate of acquisition and asymptotic level of time allocation preference in the open field

The present experiment explores the effects of the response (1-sec occupancy of a target area in an open field)-reinforcer (intracranial stimulation) contingency on time allocation in the open field in rats. The probability of reinforcement given response (X) and the probability of reinforcement given nonresponse (Y) were varied randomly across sessions within a subject. The 21 contingency treatments explored included all possible combinations of values (0, .1, .2, .3, .4, .5) of X and Y such that X ≥ Y. The results indicate that rate of acquisition and asymptotic level of time allocation preference to the target area are negatively related to the value of Y (for any given value of X). Variations in X (for any given value of Y) were less effective. Evaluation of proposed contingency metrics revealed that the Weber fraction (X − Y)/X most closely approximates performance, and that the value of the difference detection threshold derived from the Weber fraction is a constant.     

Intermodal perception of expressive behaviors by human infants

Four experiments demonstrate that infants of 5 and 7 months can detect information that is invariant across the acoustic and optic presentations of a single affective expression. Infants were presented simultaneously with two filmed facial expressions accompanied by a single vocal expression characteristic of one of the facial expressions. The infants increased their looking time to a facial expression when it was sound-specified, as compared to when that filmed expression was projected silently. Even when synchrony relations were disrupted, infants looked proportionately longer to the film that was sound-specified, indicating that some factor other than temporal synchrony guided the infants' looking behavior. When infants viewed the filmed facial expressions either in a normal orientation or upside-down, those infants viewing the facial expressions in the normal orientation looked appropriately, while those viewing the inverted films did not. These findings support the view that infants are sensitive to amodal, potentially meaningful invariant relations in expressive behaviors. These results are discussed in the context of J. J. Gibson's theory of affordances.     

Children's beliefs about adoption: A developmental study

Attributions about adoption were examined in adopted and nonadopted children between the ages of 6 and 13 years. Results indicated that nonadopted children had a more negative view of adoption than their adopted age-mates, at least during the early to middle childhood years. By 10–11 years, however, no group difference was noted in adoption beliefs. In addition, with increasing age nonadopted children became less negative about adoption whereas adopted children became more negative about adoption. These results are discussed in the context of differential socialization for adopted and nonadopted children. Implications of adoption beliefs for children's adoption adjustment also are raised.     

Attending to multiple sources of information: I. The integration of information in decision making

Information relevant to a decision is often available from several sources, such as different sensory modalities or different spatial locations. Processing or utilization of such information is often selective in that some sources seem to have more influence on a decision or response than others. Many different theoretical mechanisms have been proposed to account for such selective (i.e., attentional) aspects of human information processing. This paper considers theoretical mechanisms which operate to integrate separate sources of information in order to make a binary decision. In particular, these mechanisms are studied in simple visual and auditory detection tasks as well as a Bayesian decision problem. Data from these experiments reject the idea that one integrates the relevant information from several sources prior to making a decision. Rather, one seems to form separate decisions about the information from each source and then integrate these decisions in order to select a response.