A cost-benefit analysis of demand for food.

Laboratory studies of consumer demand theory require assumptions regarding the definition of price in the absence of a medium of exchange (money). In this study we test the proposition that the fundamental dimension of price is a cost-benefit ratio expressed as the effort expended per unit of food value consumed. Using rats as subjects, we tested the generality of this "unit price" concept by varying four dimensions of price: fixed-ratio schedule, number of food pellets per fixed-ratio completion, probability of reinforcement, and response lever weight or effort. Two levels of the last three factors were combined in a 2 x 2 x 2 design giving eight groups. Each group was studied under a series of six FR schedules. Using the nominal values of all factors to determine unit price, we found that grams of food consumed plotted as a function of unit price followed a single demand curve. Similarly, total work output (responses x effort) conformed to a single function when plotted in terms of unit price. These observations provided a template for interpreting the effects of biological factors, such as brain lesions or drugs, that might alter the cost-benefit ratio.     

Exploring sex differences in the emotional content of mother-child conversations about the past

In this study, the ways in which mothers and their 30–35-month-old children discussed the emotional aspects of past experiences was explored. Although previous research has established that children this age talk about emotions, and some studies have found sex differences between mother-daughter and mother-son dyads in these conversations, no study has examined explicitly the way in which emotions about the past are discussed. This is an important research question because emotional aspects of events may help provide an evaluative framework for thinking about and talking about the past. The results suggest that, with daughters, mothers focus more on positive emotions and tend not to attribute negative emotions to the child. With sons, positive and negative emotions are discussed equally. Moreover, mothers never discuss anger with their daughters but they do with their sons. Finally, mother-daughter conversations emphasize the emotional state itself, whereas mother-son conversations often discuss the causes and consequences of emotions. The way in which these patterns might contribute to children's developing understanding of gender-appropriate emotional reactions are discussed.     

Manipulation of self-destruction in three retarded children

The study attempted to isolate some of the environmental conditions that controlled the self-destructive behavior of three severely retarded and psychotic children. In the extinction study subjects were placed in a room where they were allowed to hurt themselves, isolated from interpersonal contact. They eventually ceased to hurt themselves in that situation, the rate of self-destruction falling gradually over successive days. In the punishment study, subjects were administered painful electric shock contingent on the self-destructive behavior. (1) The self-destructive behavior was immediately suppressed. (2) The behavior recurred when shock was removed. (3) The suppression was selective, both across physical locales and interpersonal situations, as a function of the presence of shock. (4) Generalized effects on other, non-shock behaviors, appeared in a clinically desirable direction. Finally, a study was reported where self-destructive behavior increased when certain social attentions were given contingent upon that behavior.     

The early development of empathy: Self-regulation and individual differences in the first year

A longitudinal study of 45 mothers and their first-born infants was conducted to identify developmentally meaningful, individual differences in children's primitive empathic responding at 12 months of age, and to determine whether differences in self-regulatory skills assessed at 4 months might underlie any differences in empathic responding observed. Personal distress responses analogous to those observed in older children and adults were identified in one-third of the sample at 12 months of age. These distress responses were associated with indices of poorer self-regulatory skills in social contexts at 4 months of age. The results are interpreted within the broader framework of the development of self-regulatory strategies in the early childhood years.This research was supported by grants from the Australian Research Council, the National Research Fellowship Scheme, and the Macquarie University Research Grant Scheme. We thank Judy Chan, Alison Malbourne, Sylvana Sturevska, and Lorraine Smith for their assistance in data collection and analysis.     

Young Children′s Event Recall: Are Memories Constructed through Discourse?

The ways in which event memories may be reconstructed or transformed through discussion with others is a critical question both for understanding basic memory processes and for issues concerning legal testimony. In this research, white middle-class preschool children were interviewed first by their mothers and then by a female experimenter about personally experienced events when they were 40, 46, 58, and 70 months of age. Analyses indicated that at all four time points children only incorporated about 9% of the information initially recounted by the mother into their independent recall of the event with the experimenter. Moreover, children only repeated about 20% of the information they themselves recalled across the two interviews. Additional analyses indicated that information mutually discussed by the mother and child was no more likely to be incorporated or repeated when recalling the event with the experimenter than information not mutually discussed. These results indicate that young children′s personal memories are not so fragile that they easily incorporate information provided by another into their own recall.     

Helping Unrelated Strangers: Physical and Psychological Reactions to the Bone Marrow Donation Process Among Anonymous Donors1

The development of models that predict outcomes of voluntary action is important for practitioners who manage large groups of volunteers. In accordance with this goal, a path model was generated linking predonation characteristics of volunteer marrow donors to postdonation physical and psychological reactions. Questionnaire data were collected from 343 individuals registered to donate marrow to unrelated strangers at 3 time points: shortly predonation, shortly postdonation, and 1-year post- donation. Although donors had generally positive reactions to donation, a substantial minority reported ambivalence about donating, physical difficulty with donation, and negative psychological reactions postdonation. In addition, our data suggest that predonation ambivalence is a central predictor of postdonation reactions, even after other donor characteristics are taken into account. These results have practical implications for the recruitment of volunteers, and suggest important variables to be considered in evaluating potential bone marrow donors.     

Response Timing Accuracy as a Function of Movement Velocity and Distance

In two experiments, patterns of response error during a timing accuracy task were investigated. In Experiment 1, these patterns were examined across a full range of movement velocities, which provided a test of the hypothesis that as movement velocity increases, constant error (CE) shifts from a negative to a positive response bias, with the zero CE point occurring at approximately 50% of maximum movement velocity (Hancock & Newell, 1985). Additionally, by examining variable error (VE), timing error variability patterns over a full range of movement velocities were established. Subjects (N = 6) performed a series of forearm flexion movements requiring 19 different movement velocities. Results corroborated previous observations that variability of timing error primarily decreased as movement velocity increased from 6 to 42% of maximum velocity. Additionally, CE data across the velocity spectrum did not support the proposed timing error function. In Experiment 2, the effect(s) of responding at 3 movement distances with 6 movement velocities on response timing error were investigated. VE was significantly lower for the 3 high-velocity movements than for the 3 low-velocity movements. Additionally, when MT was mathematically factored out, VE was less at the long movement distance than at the short distance. As in Experiment 1, CE was unaffected by distance or velocity effects and the predicted CE timing error function was not evident.