Variable-ratio versus variable-interval schedules: response rate, resistance to change, and preference

Two experiments asked whether resistance to change depended on variable-ratio as opposed to variable-interval contingencies of reinforcement and the different response rates they establish. In Experiment 1, pigeons were trained on multiple random-ratio random-interval schedules with equated reinforcer rates. Baseline response rates were disrupted by intercomponent food, extinction, and prefeeding. Resistance to change relative to baseline was greater in the interval component, and the difference was correlated with the extent to which baseline response rates were higher in the ratio component. In Experiment 2, pigeons were trained on multiple variable-ratio variable-interval schedules in one half of each session and on concurrent chains in the other half in which the terminal links corresponded to the multiple-schedule components. The schedules were varied over six conditions, including two with equated reinforcer rates. In concurrent chains, preference strongly overmatched the ratio of obtained reinforcer rates. In multiple schedules, relative resistance to response-independent food during intercomponent intervals, extinction, and intercomponent food plus extinction depended on the ratio of obtained reinforcer rates but was less sensitive than was preference. When reinforcer rates were similar, both preference and relative resistance were greater for the variable-interval schedule, and the differences were correlated with the extent to which baseline response rates were higher on the variable-ratio schedule, confirming the results of Experiment 1. These results demonstrate that resistance to change and preference depend in part on response rate as well as obtained reinforcer rate, and challenge the independence of resistance to change and preference with respect to response rate proposed by behavioral momentum theory.     

Trust, Dependency, and Control in the Contemporary Organization

Trust is an essential element in productive and effective intraorganizational communication and interaction. The present study examined several consequences of trust in terms of influence strategies used and the frequency with which people interact with each other. The study also examined the extent to which the technology of work affects management's dependency on their employees. It was found that distrust of subordinates by managers (n = 275) was associated with the use of strong tactics of influence, little dependency on employees, and the use of personal-related characteristics to explain distrust. It was also found that distrust of managers by subordinates (n = 267) was associated with the use of strong methods of influence, less interaction, less attempts to influence, and the use of personal-related characteristics to explain lack of trust. These findings have clear implications for understanding the relation among worker trust, dependency, and social influence. The data suggest that both employees and employers could benefit from considering the importance of a trusting relationship in the workplace.     

“I Was Really, Really, Really Mad!” Children's Use of Evaluative Devices in Narratives About Emotional Events

Children (ages 3, 5, and 8 years, mostly White and middle-class) were asked to tell personal experience narratives about a time when they had been happy, surprised, and mad. Their explicit emotion labels as well as their use of linguistic forms of evaluation to convey emotion were assessed. Five-year-old boys were the most likely to explicitly label anger, while gender and age differences in explicit emotion labels were absent for the other two emotions. However, children used many more linguistic devices for providing evaluation than explicit emotion labels in their narratives. They also provided more with age, and they used more evaluative devices when talking about anger-arousing events than about happy or surprising events. The few gender differences suggested that 3-year-old girls may acquire earlier mastery of evaluative devices than do boys, especially references to emotional states.     

The Effects of a List of Food Items on Motivations to Eat in Dieters and Nondieters

A major health problem in our society is obesity, which is frequently caused by overeating or eating inappropriate foods. It has been suggested that the prevalences of food and food-related cues contribute to overeating and that dieters are particularly sensitive to food stimuli. In the present study, the influence of dieting was examined in a representative sample of college students who were exposed to a list of written food cues or who served as controls. The list of food cues increased motivation to eat in nondieting subjects, but did not appear to influence the appetites of dieters. It may be that dieters are more resistant to the effects of more subtle food cues, even when many cues are presented sequentially.     

More accurate size contrast judgments in the Ebbinghaus Illusion by a remote culture

The Ebbinghaus (Titchener) illusion was examined in a remote culture (Himba) with no words for geometric shapes. The illusion was experienced less strongly by Himba compared with English participants, leading to more accurate size contrast judgments in the Himba. The study included two conditions of inducing stimuli. The illusion was weaker when the inducing stimuli were dissimilar (diamonds) to the target (circle) compared with when they were similar (circles). However, the illusion was weakened to the same extent in both cultures. It is argued that the more accurate size judgments of the Himba derive from their tendency to prioritize the analysis of local details in visual processing of multiple objects, and not from their impoverished naming.     

Parent–child talk and children's memory for stressful events

The relationship between parents' styles of talking about past events with their children and children's recall of stressful events was explored. In this investigation, 2‐ to 5‐year‐old children's recall of injuries requiring hospital emergency room treatment was assessed within a few days of the injury and again 2 years later, along with the way their parents reminisced with them about the event. Correlational analyses showed that age and parental reminiscing style were consistently related to child memory; regression analyses showed that although age was most important, parents who were more elaborative had children who recalled more during their initial interview about the harder‐to‐remember hospital event. Thus, an elaborative parental style may help children's recall of even highly salient and stressful events. Copyright © 2006 John Wiley & Sons, Ltd.     

Visual attention as a predictor of on-road driving performance of older drivers

With increasing numbers of older drivers on Australian roads, it is important to determine the functional abilities most closely related to driving ability among older adults. To this end, 90 drivers aged from 60 to 91 completed a battery of psychological, visual, physical and cognitive tests, and a standardised on-road driving test. A computerised test of visual attention, devised specifically for the study, was the best predictor of on-road driving performance. Other abilities that made independent contributions to the prediction of driving performance were contrast sensitivity and visuospatial memory. These functional abilities provided a better prediction of driving performance than chronological age, reinforcing the argument that drivers should only have their driving tested when their functional abilities decline, rather than when they reach a particular age.     

Combining attributes in rapid serial visual presentation tasks

A series of three exploratory experiments sought to compare and contrast two broad classes of theory pertaining to visual information pick-up. One theoretical approach, exemplified by Keele and Neill (1978) and by Treisman (1977) emphasizes the relatively passive, parallel development of information codes, with subsequent attentional integration of contiguous codes into a percept. Another theoretical approach, exemplified by Broadbent (1977a) emphasizes the relatively active, sequential, recursive interrogation of a visual display in which the pick-up of each piece of information guides the perceptual system in its quest for more information. The manner in which separable attributes of visual information are picked up and combined was studied by manipulating the roles of different attributes in a rapid serial visual presentation (RSVP) paradigm. Observers were asked to report the name of a letter in a specified target colour; to report the colour of a specified target letter; to report the colour of a specified target numeral embedded in a list of letters; to report the colour of an unspecified numeral embedded in a list of letters; and to perform the latter two tasks without knowing in which of two alternating spatial positions the target might appear. Examination of the patterns of mis-combinations of attributes from target and non-target stimuli yields evidence both for and against each theoretical position, and suggests that the two might better be considered as modes of processing available to the perceptual system, rather than as intrinsic properties of that system.     

The contribution of the thumb to reaching movements

Transport of the hand towards an object and the formation of grasp are logically separable components of reaching. It has been suggested that, although the two components must be temporally co-ordinated, their spatial parameters are under the control of independent visuo-motor channels. A case study of reaching by a proficient user of a manually-operated artificial hand is presented. A pattern of natural hand usage was observed in which the index finger rather than the thumb was responsible for reduction of grasp aperture as the hand approached an object. The same pattern of usage was also observed in the artificial hand even though the mechanics of that hand make it no easier to move the finger than the thumb. This suggests that the relative stability of the thumb in the natural hand is determined, not simply by anatomy, but by a role in guiding the transport component of reaching. At least part of the spatial aspect of grasp formation is closely related to the transport component of reaching and this is evidence against theories postulating two independent visuo-motor channels controlling the spatial parameters of grasp and transport.