Open versus closed economies: performance of domestic hens under fixed ratio schedules

Domestic hens responded under fixed-ratio schedules of food (wheat) reinforcement under several experimental conditions. Part 1 (open economy) investigated performance on fixed-ratio schedules over both multisession steady-state conditions and daily changes of the schedule, with hens maintained at 80% of free-feeding weights by extraexperimental feeding. In Parts 2 and 3 (closed economy and short sessions) sessions were 40 min long, and the hens' weights were allowed to vary (Part 2) or sessions were conducted only when the hens were at approximately 80% of free-feeding weights (Part 3). In Part 4 (closed economy and long sessions) sessions were 24 hr long and the fixed-ratio requirement was changed either daily or after 7 consecutive days. In general, the daily changes of fixed-ratio requirement in the open economy and short-session closed economy gave much the same result as the steady-state open-economy sessions. Overall response and reinforcer rates decreased with increasing fixed-ratio requirement (except at the shortest fixed ratios). Running response rates decreased, and postreinforcement pauses generally increased. In contrast, overall response rates in the long-session closed economy generally increased with the fixed-ratio requirement. Session length is suggested as a cause of the differences between the short- and long-session closed-economy results.     

Disablement and eye contact

This study investigated the effect of height level and wheelchair presence on eye contact and interaction. Presence of a wheelchair increased eye contact to a standing colleague, possibly due to the wheelchair-confined individuals' perceived dependence on others.     

Commitment, pro-relationship behavior, and trust in close relationships

The present work advances and tests an interdependence-based model of the associations among commitment, pro-relationship behavior, and trust. Findings from two longitudinal studies revealed good support for model predictions. Commitment-inspired acts such as accommodation and willingness to sacrifice provide diagnostic information regarding a partner's pro-relationship motives. Individuals come to trust their partners when they perceive that their partners have enacted pro-relationship behaviors, departing from their direct self-interest for the good of the relationship. The results of mediation analyses are consistent with a model of mutual cyclical growth in which (a) dependence promotes strong commitment, (b) commitment promotes pro-relationship acts, (c) pro-relationship acts are perceived by the partner, (d) the perception of pro-relationship acts enhances the partner's trust, and (e) trust increases the partner's willingness to become dependent on the relationship. Auxiliary analyses revealed that self-reported attachment style does not account for substantial variance beyond the features of interdependence that form the basis for the present model.     

The effects of differing response types and price manipulations on demand measures

Animals' behavioral needs have become an important component of animal welfare legislation. Behavioral economics provides a framework for the study of such needs. A function, analogous to a demand function relating consumption rate to price, can be obtained by increasing the price (or work) required for access to a commodity. This experiment investigated the effects of different response types and price manipulations on these functions. Six hens pushed a door or pecked a key for food under open economic conditions (short experimental sessions and supplementary food). In Part 1, the number of door pushes required (fixed-ratio schedule) was increased each session, and the force needed to push the door was increased across conditions. In Part 2, the force needed to push the door was increased session to session, and the fixed-ratio schedule was increased across conditions. In Part 3, the number of key pecks required was increased each session. Both response types produced similarly shaped (approximately linear in logarithmic coordinates and downward sloping) demand functions when price was increased by increasing the number of responses required. These imply an elastic demand for food under these conditions. In contrast, increasing the force required to push the door resulted in highly curvilinear functions. These functions indicated little change in consumption across lower door forces and abrupt drops in consumption at higher force requirements, implying mixed elasticity in the animals' demand for food. The differences between the shapes of the two functions seem to arise from the different ways that the two price manipulations alter the time taken to complete the work required. Increasing the fixed-ratio requirement necessarily increases the time needed to complete each response unit, whereas increasing the force requirement does not. The different shapes of the functions were robust when either force or number was varied across sessions and the value of the other was varied over conditions. They were also robust when the price increases were taken from different conditions, showing that the shapes of the functions were independent of the place in the experiment in which the price was examined. Unit price (which combines number and force into a single price measure) unified the data from the two price manipulations to a large degree, producing moderately curved functions. However, there was some variance around the unit price functions, and this was attributable to the different shapes of the underlying functions. The data suggest that different price manipulations may give different measures of animal demand but that unit price might provide some unification.     

The transitivity of choices between different response requirements

This experiment tested the transitivity of hens' choices between response requirements differing in both form and number. In a concurrent second-order schedule procedure, 6 hens chose between two alternatives by making either key-peck or door-push responses. The reinforcement rates on the two alternatives remained constant and equal throughout conditions, but the number of responses (i.e., key pecks or door pushes) required on each alternative was varied by changing the second-order (fixed-ratio) requirements. The preferences obtained from two pairings of response requirements allowed prediction of the preferences expected in a third pairing. No intransitivities were found, implying that the response requirements lie on a common unitary scale of value. For response-based measures, the obtained preferences varied evenly around perfect, multiplicative prediction, and all satisfied strong transitivity, implying an underlying interval scale of value. For time-based measures, only moderate transitivity was satisfied, implying only an ordinal scale of value. Time-based measures were confounded with the differing times taken to complete each response requirement. The existence of such scales indicates that direct comparisons of different response requirements may be possible.     

Acting Out Against Gender Discrimination: The Effects of Different Social Identities

Self-categorization theory suggests thatwhen asocialidentity is salient,grouporiented behavior willensue. Thus, women should be likely to actoutagainstgender discrimination when their social identity as women is salient. However,self-categorization theory has typically defined asocial identity along stereotypes, which may serveinstead to maintain the status quo. Two studiestherefore examined the effects of two different social identities ontaking action against discrimination. Participants werefemale students (Anglo American (93%), African American(2%), Native American (2%), Hispanic (1%), Asian American (1%)and Other (1%)). Study 1 examineda structural model and Study 2 examined the causalrelationships, both hypothesizing that a social identitybased on stereotypes would be associated with less collective action than a social identity basedon social experiences. The hypothesis was supported, andimplications for expanding definitions of socialidentities were discussed.     

Spatial and relational frameworks for free recall in young and older adults

Previous studies have demonstrated that older adults can use visually distinctive cues to enhance their spatial memory performance and their recall of the identities of items located in space. Other research has shown that older adults can also use relational information to enhance recall. The relationship between relational and visuospatial support for memory across the adult lifespan is complex and has been little explored. In the present study, this relationship was examined in tasks that measured free recall for item sets possessing different degrees of visuospatial and relational support for recall. It was predicted that both types of support would enhance older adult recall relative to that of the young, and that the two types of support would synergize. The results were generally consistent with these predictions. These findings show that older adults can use relatively simple relational or visuospatial support systems to enhance free recall significantly. This research was supported by Grant AGI 1605, National Institute on Aging.     

The hippocampus and delayed recall: bigger is not necessarily better?

Healthy young female participants were tested on a measure of delayed verbal recall and then received volumetric Magnetic Resonance Imaging (MRI) scans. The analysis of the MRI scans focused on the volume of the hippocampus. Left hippocampal volume was negatively associated with the level of delayed verbal recall performance. This relationship was confirmed in further testing. This finding is consistent with a previous report of a similar relationship in healthy elderly individuals, but not in patients with Alzheimer's disease, in whom the opposite relationship was observed. An explanation of these findings in terms of impaired neural pruning of the hippocampus is advanced, whereby insufficient pruning of the hippocampus during childhood and adolescence (following adequate growth) may lead to reduced mnemonic efficiency.     

The movement-activated recording monitor: A third-generation motor-activity monitoring system

The movement-activated recording monitor (MARM) is a small noninvasive device that continuously detects, accumulates, and stores the amount of motor activity produced during sequential time intervals of designed duration. If motor activity totals are recorded every 15 min, the MARM is capable of calculating and storing 96 data points/day for 5.33 days. The MARM employs large-scale-integrated complementary-metal-oxide integrated circuits. To date, application has been primarily limited to psychiatric investigations, but the MARM is readily applicable for other time-motion studies of human or animal subjects.     

A computer-compatible multichannel event counting and digital recording system

An inexpensive multichannel event counting digital recording system has been designed for compatibility with automated data analysis equipment. For as many as 16 channels, events are simultaneously summed over preselected repetitive time intervals and recorded. Each data entry is marked with the time of day and a code identifying each channel’s data. The data is formated to be computer compatible and is logged on inexpensive readily available digital magnetic tape cassettes.