Preference after training with differential changeover delays

Pigeons were trained on a multiple schedule in which each component consisted of concurrent variable-interval (VI) 30-s VI 60-s schedules. The two components of the multiple schedule differed only in terms of the changeover delays (COD): For one component short CODs were employed, and in the second component long CODs were used. After approximate matching was obtained in each component, probe tests involving new combinations of stimuli were presented (e.g., the VI 30-s schedule from each component) to determine how the different CODs affected preference. Despite shorter CODs producing higher changeover rates, the COD value had no systematic effect on preference on the probe trials. However, differences in reinforcement rate always produced preference for the schedule with the higher reinforcement rate. The results thus show that the the pattern of changeover behavior per se is not a critical determinant of choice in the probe-trial procedure.     

Infants’ responses to objects representing levels of word knowledge and categorical information

The effects of differing levels of word knowledge on infants’ sequential touching behaviors were investigated in two studies. In both, parent report was used to assess three levels of word knowledge: known, frontier, and unknown. In the first study, 14-month-old infants sequentially touched objects consistent with parents’ reports of their word knowledge. In the second study, 20-month-old infants sequentially touched objects by both conceptual category and reported level of word knowledge. It appears that even infants, like adults, can make distinctions among objects on the basis of their knowledge about the objects’ labels.     

Closing the gap between behavior and models in route choice: The role of spatiotemporal constraints and latent traits in choice set formation

A considerable gap exists between the behavioral paradigm of choice set formation in route choice and its representation in route choice modeling. While travelers form their viable choice set by retaining routes that satisfy spatiotemporal constraints, existing route generation techniques do not account for individual-related spatiotemporal constraints. This paper reduces the gap by proposing a route choice model incorporating spatiotemporal constraints and latent traits. The proposed approach combines stochastic route generation with a latent variable semi-compensatory model representing constraint-based choice set formation followed by compensatory choice. The model is applied to data focusing on habitual commuting route choice behavior in morning peak hours. Results show (i) the possibility of inferring spatiotemporal constraints from considered routes, (ii) the importance of incorporating spatiotemporal constraints and latent traits in route choice models, and (iii) the linkage between spatiotemporal constraints and time saving, spatial and mnemonic abilities.     

Israeli Students' Perspectives Concerning Determinants of Intelligence

Abstract

Students' attitudes toward the nature versus nurture controversy pertaining to a variety of critical phenomena in the intelligence domain were assessed. A student inventory was constructed, pretested, and group administered to 269 students in various academic institutions in northern Israel, and comparisons were made between various sex, social, and ethnic groups. The majority of the students maintained that environment is the main factor influencing both personality and intelligence. Environment and an Environment x Heredity interaction were the most popular categories used to explain various generalizations about differences in ability, particularly among lower-class students. Students of Western origin were more inclined to adopt an environmental perspective on differences in IQ than were their Eastern counterparts. No sex differences were observed.     

Concurrent-chains schedules as a method to study choice between alcohol-associated conditioned reinforcers

An extensive body of research using concurrent-chains schedules of reinforcement has shown that choice for one of two differentially valued food-associated stimuli is dependent upon the overall temporal context in which those stimuli are embedded. The present experiments examined whether the concurrent chains procedure was useful for the study of behavior maintained by alcohol and alcohol-associated stimuli. In Experiment 1, rats responded on concurrent-chains schedules with equal variable-interval (VI) 10-s schedules in the initial links. Across conditions, fixed-interval schedules in the terminal links were varied to yield 1∶1, 9∶1, and 1∶9 ratios of alcohol delivery. Initial-link response rates reflected changes in terminal-link schedules, with greater relative responding in the rich terminal link. In Experiment 2, terminal-link schedules remained constant with a 9∶1 ratio of alcohol delivery rates while the length of two equal duration initial-link schedules was varied. Preference for the rich terminal link was less extreme when initial links were longer (i.e., the initial-link effect), as has been previously reported with food reinforcers. This result suggests that the conditioned reinforcing value of an alcohol-associated stimulus depends on the temporal context in which it is embedded. The concurrent-chains procedure and quantitative models of concurrent chains performance may provide a useful framework within which to study how contextual variables modulate preference for drug-associated conditioned reinforcers.     

SAVING THE BEST FOR LAST? A CROSS-SPECIES ANALYSIS OF CHOICES BETWEEN REINFORCER SEQUENCES

Two experiments were conducted to compare choices between sequences of reinforcers in pigeon (Experiment 1) and human (Experiment 2) subjects, using functionally analogous procedures. The subjects made pairwise choices among 3 sequence types, all of which provided the same overall reinforcerment rate, but differed in their temporal patterning. Token reinforcement schedules were used in both experiments and the type of exchange schedule varied across blocks of sessions. Some conditions permitted immediate exchange of tokens for consumable reinforcers (food for pigeons, video access for humans); in other conditions, tokens accumulated and were exchanged for consumable reinforcers only at the end of the sequence. Choice patterns in the immediate-exchange conditions were generally similar across species, with both pigeons and humans preferring sequences with the shortest delay to the initial reinforcer in the series. The results are broadly consistent with models of temporal discounting expanded to include the impact of sequences of delayed reinforcers acting in parallel from the time of the choice. Preferences were less consistent with discounting models in the delayed exchange conditions. Questionnaire data gathered at the end of the experiment were consistent with prior results of questionnaire studies, but showed no straightforward relation to the observed choice patterns, urging caution in the extrapolation of results from one decision-making domain to the other.     

Normative influence on retirement savings decisions: Do people care what employers and the government want?

The need for Australians to increase retirement savings has been widely promoted. Yet our understanding of the motivations of individuals to save at a higher rate remains sparse. This article reports the findings of a survey of superannuation fund members and their intentions to contribute more to superannuation and to manage their investment strategy. The article uses the theory of planned behaviour to focus on the important motivational influence of social norms. Formative research identified a number of influential social referents. Among identified referents, the study found that spouses appear to be the primary source of social influence for retirement savings decisions. The government and employers appear to exert little influence, and financial advisors and superannuation funds take up the middle ground of social influence. Possibilities for interventions designed to influence behaviour are discussed; however, conclusions are tempered by the fact that correspondence between intention and behaviour is not tested in the present research.     

The preference for symmetry in flower-naïve and not-so-naïve bumblebees

Truly flower-naïve bumblebees, with no prior rewarded experience for visits on any visual patterns outside the colony, were tested for their choice of bilaterally symmetric over asymmetric patterns in a radial-arm maze. No preference for symmetry was found. Prior training with rewarded black and white disks did, however, lead to a significant preference for symmetry. The preference was not specific to symmetry along the vertical axis: a preference for horizontal symmetry was found as well. The results challenge the notion that a preference for bilateral symmetry is unlearned. The preference for symmetry was the product of non-differential conditioning.     

Transitional and steady-state choice behavior under an adjusting-delay schedule

Twelve rats made repeated choices on an adjusting-delay schedule between a smaller reinforcer (A) that was delivered immediately after a response and a larger reinforcer (B) that was delivered after a delay which increased or decreased by 20% depending on the subject's choices in successive blocks of trials. In two phases of the experiment (100 sessions and 40 sessions), reinforcer sizes were selected which enabled theoretical parameters expressing the rate of delay discounting and sensitivity to reinforcer size to be estimated from the ratio of the indifference delays obtained in the two phases. Indifference delays, calculated from adjusting delays in the last 10 sessions of each phase, were shorter when the sizes of A and B were 14 and 25 μl of a 0.6 M sucrose solution than when they were 25 and 100 μl of the same solution. The ratio of the indifference delays was significantly smaller than that predicted on the basis of an assumed linear relation between reinforcer size and instantaneous reinforcer value, consistent with a previous proposal that this relation may be hyperbolic in form. Estimates of the rate of delay discounting based on the ratio of the two indifference delays (mean, 0.08 s(-1)) were similar to values obtained previously using different intertemporal choice protocols. Estimates of the size-sensitivity parameter (mean 113 μl) were similar to estimates recently derived from performance on progressive-ratio schedules. In both phases of the experiment, adjusting delays in successive blocks of trials were analyzed using the Fourier transform. The power spectrum obtained from individual rats had a dominant frequency that corresponded to a period of oscillation of the adjusting delay between 30 and 100 trial blocks (mean, 78). Power in the dominant frequency band was highest in the early sessions of the first phase and declined with extended training. It is suggested that this experimental protocol may have utility in neurobehavioral studies of intertemporal choice.