Effects of reinforcement magnitude and ratio values on behaviour maintained by a cyclic ratio schedule of reinforcement

In Experiments 1 and 2, lever pressing by rats was reinforced on a cyclic ratio schedule of food reinforcement, comprising a repeated sequence of fixed-ratio component schedules. Reinforcement magnitude was varied, on occasional sessions in Experiment 1 and across blocks of sessions in Experiment 2, from one to two or three 45-mg food pellets. In the one-pellet condition, post-reinforcement pauses increased with component schedule value. At higher magnitudes, post-reinforcement pauses increased, and overall response rates declined. Response rate on component schedules was a decreasing linear function of the obtained rate of reinforcement in all conditions. Plotted against component schedule value, response rate increased exponentially to an asymptote that decreased when reinforcement magnitude increased. These findings are consistent with regulatory accounts of food reinforced behaviour. In Experiment 3, rats were trained under a cyclic ratio schedule comprising fixed-ratio components including higher values, and some inverted U-shaped response functions were obtained. Those rats that did not showthis relationship were trained on cyclic ratios with even higher values, and all showed inverted U-shaped response functions. This suggests that behaviour on cyclic ratio schedules can reflect activating of reinforcement as well as the satiating effects seen in Experiments 1 and 2.     

Behavioral contrast: Research and areas for investigation

Behavioral contrast occurs when a change in reinforcement rate in one context results in a change in behavior in the opposite direction in an unchanged context. Despite decades of study by basic researchers, behavioral contrast has remained largely an unstudied phenomenon among applied researchers. The purpose of this paper is to occasion translational and applied research on behavioral contrast with the aim of predicting and controlling socially significant behavior in unchanged contexts. We present a brief history of contrast and related definitions, review research with human and nonhuman subjects, and suggest future directions for applied and translational researchers.     

The paramenstruum and negative moods in normal young women

The present study investigated the effects of depressogenic statements on 154 normal young women, in relation to the late luteal phase of the female monthly cycle (paramenstruum). The women were allocated to a depressive-induction group or to either of two non-treatment groups. Multivariate ANOVAs indicated that paramenstrual women given the depressogenic statements reported more negative post-induction mood states than did other women. Four of the 12 mood states measured by the Differential Emotions Scale (DES-IV) were significantly elevated for the paramenstrual women in the depressive-induction group only (viz. Sadness, Hostility, Fear and Shame subscales). It was concluded that paramenstrual women appear to be more sensitive to depressive stimuli, and therefore, more prone to experience negative mood states than women at other stages in their monthly cycles.     

A reanalysis of the higher-order factor structure of the motivation analysis test and the eight state questionnaire

In an exploratory study of the higher-order factor structure of the Motivation Analysis Test (MAT) and the Eight State Questionnaire (8SQ), Boyle (1983c) obtained an 11-factor solution comprising 9 second-order MAT factors and 2 higher-order 8SQ factors. However, application of more conservative criteria regarding the size of significant factor pattern loadings, significance of derived factors, together with reinterpretation of the appropriate Scree ‘break’, suggest that in Boyle's earlier analysis 2 factors too many were extracted. Recalculation of the factor pattern for the MAT (using 8SQ data as ‘hyperplane stuff’) supports the view that 7 rather than 9 second-order MAT factors were appropriate. A separate dR-factoring of the intercorrelations of the subscale difference scores indicated 3 higher-order 8SQ factors, indicative of change dimensions, and not 2 factors as found in the static single-occasion combined factoring of both the MAT and 8SQ data.     

Prospective versus retrospective assessment of Menstrual cycle symptoms and moods: Role of Attitudes and beliefs

Prospective vs. retrospective self-reports of menstrual cycle symptoms and moods in users and nonusers of oral contraceptives were investigated. Subjects, aged from 17 to 27 years, included 56 women on the pill and 47 nonusers. The Menstrual Distress Questionnaire (MDQ) quantified physical symptomatology, while the Differential Emotions Scale (DES-IV) measured emotional states. Prospective reports suggested less discernible symptom and mood effects than did retrospective reports. Physical symptoms were significantly higher menstrually than premenstrually, whereas negative affects increased premenstrually. Women on the pill reported significantly fewer symptoms and negative moods than nonusers, although there were no significant differences in positive mood states. Menstrual Attitude Questionnaire (MAQ) scores suggested that nonusers of oral contraceptives found menstruation more debilitating than those on the pill. Based on a paper presented at the 5th Biennial Conference of the International Society for the Study of Individual Differences, Department of Experimental Psychology, Oxford University, July 22–26, 1991.     

Electromyographic responses in infants after auditory stimulation.

49 of 50 newborn infants, when presented with a strong auditory stimulus, showed significant increases in EMG potential. The infant who failed initially responded when rechecked in 1 mo. The results suggest it may be possible to develop an EMG-Audiometric process which could be employed in screening hearing of newborn infants.     

Independent processing of form, colour, and texture in object perception

Most investigations of object recognition have focused on the form rather than the material properties of objects. Nevertheless, knowledge of the material properties of an object (via its surface cues) can provide important information about that object's identity. In this study, we used Garner's speeded-classification task to explore whether or not the processing of form and the processing of surface properties are independent. In experiment 1, participants made length and width classifications in an initial form task. Participants were unable to ignore length while making width classifications, and were unable to ignore width while making length classifications. This suggests that the perception of length and the perception of width share common processing resources. In a subsequent task, we examined possible interactions between the processing of form and the processing of surface properties. In contrast to the findings with the form task, participants were able to ignore form while making surface-property classifications, and to ignore surface properties while making form classifications. This suggests that the form of objects and their surface properties are processed independently. In experiment 2, we went on to show that the two prominent surface-property dimensions of colour and texture can also be processed independently. In other words, participants were able to ignore colour while making texture classifications, and vice versa. Finally, in experiment 3, we examined the possibility that the stimuli and required responses that we used in experiment 2 were too categorical and thus not optimal for assessing whether or not colour and texture share common processing resources. Using a different stimulus set, participants were again able to ignore colour while making texture classifications, and vice versa. Taken together, these results provided convincing evidence that the separate ventral-stream brain regions identified for form, texture, and colour in a recent neuroimaging study (Cant and Goodale, 2007 Cerebral Cortex 17 713-731) can indeed function independently.     

Learning to Neighbor? Service-learning in Context

Service-learning has received a great deal of attention in the management education literature over the past decade, as a method by which students can acquire moral and civic values as well as gain academic knowledge and practice real-world skills. Scholars focus on student and community impact, curricular design, and rationale. However, the educational environment (“context”) in which service-learning occurs has been given less attention, although experienced educators know that the classroom is hardly a vacuum and that students learn a great deal from the non-curricular aspects of their educational experience. Moral values in particular are conveyed by what is not said. Given this, I argue that the contexts in which service-learning takes place are as important as the activity itself. Three perspectives on context will be described and assessed: the “hidden” curriculum, the educational atmosphere, and the university’s orientation towards social responsibility.