DISCOUNTING OF DELAYED FOOD REWARDS IN PIGEONS AND RATS: IS THERE A MAGNITUDE EFFECT?

Temporal discounting refers to the decrease in the present, subjective value of a reward as the time to its receipt increases. Results from humans have shown that a hyperbola-like function describes the form of the discounting function when choices involve hypothetical monetary rewards. In addition, magnitude effects have been reported in which smaller reward amounts are discounted more steeply than larger amounts. The present research examines the cross-species generality of these findings using real rewards, namely food pellets, with both pigeons and rats. As with humans, an adjusting amount procedure was used to estimate the amount of immediate reward judged equal in value to a delayed reward. Different amounts of delayed food rewards (ranging from 5 to 32 pellets in pigeons and from 5 to 20 pellets in rats) were studied at delays varying from 1 s to 32 s. A simple hyperbola, similar to the hyperbola-like mathematical function that describes the discounting of hypothetical monetary rewards in humans, described the discounting of food rewards in both pigeons and rats. These results extend the generality of the mathematical model of discounting. Rates of discounting delayed food rewards were higher for pigeons than for rats. Unlike humans, however, neither pigeons nor rats showed a reliable magnitude effect: Rate of discounting did not vary systematically as a function of the amount of the delayed reward.     

Haunted by parents--a literary example of change meaning loss: Edna St. Vincent Millay

The author uses the life and personal history of the poet Edna St. Vincent Millay, as revealed through her diaries and letters and in biographies, to illustrate a particular type of psychoanalytic patient. Such patients are resistant to change, particularly when it involves letting go of the internalization of early parental figures. Although some of these patients fail to achieve successful analytic outcomes, Millay is an example of someone with similar circumstances who nevertheless made significant creative contributions.     

Testing predictions of the interactive activation model in recovery from aphasia after treatment

This paper presents preliminary results of pre- and post-treatment error analysis from an aphasic patient with anomia. The Interactive Activation (IA) model of word production (Dell, Schwartz, Martin, Saffran, & Gagnon, 1997) is utilized to make predictions about the anticipated changes on a picture naming task and to explain emerging patterns. Error patterns are viewed in light of two putative mechanisms within the IA network, connection strength, and rate of decay. The results suggest that while these mechanisms can successfully account for the magnitude and order of specific errors (e.g., predominance of semantic paraphasias and nonwords followed by formal paraphasias under the conditions of weak connections), the treatment may have influenced the occurrence/absence of some error types.     

The Development of Aggression in 18 to 48 Month Old Children of Alcoholic Parents

This study examined the development of aggressive and oppositional behavior among alcoholic and nonalcoholic families using latent growth modeling. The sample consisted of 226 families assessed at 18, 24, 36, and 48 months of child age. Results indicated that children in families with nonalcoholic parents had the lowest levels of aggressive behavior at all time points compared to children with one or more alcoholic parents. Children in families with two alcoholic parents did not exhibit normative decreases in aggressive behavior from 3 to 4 years of age compared to nonalcoholic families. However, this association was no longer significant once a cumulative family risk score was added to the model. Children in families with high cumulative risk scores, reflective of high parental depression, antisocial behavior, negative affect during play, difficult child temperament, marital conflict, fathers’ education, and hours spent in child care, had higher levels of aggression at 18 months than children in low risk families. These associations were moderated by child gender. Boys had higher levels of aggressive behavior at all ages than girls, regardless of group status. Cumulative risk was predictive of higher levels of initial aggressive behavior in both girls and boys. However, boys with two alcoholic parents had significantly less of a decline in aggression from 36 to 48 months compared to boys in the nonalcoholic group.     

Les passions de l'ame: on obsessive and harmonious passion

Passion is defined as a strong inclination toward an activity that people like, that they find important, and in which they invest time and energy. Two types of passion are proposed: obsessive and harmonious. Obsessive passion (OP) refers to a controlled internalization of an activity in one's identity that creates an internal pressure to engage in the activity that the person likes. Harmonious passion (HP) refers to an autonomous internalization that leads individuals to choose to engage in the activity that they like. HP promotes healthy adaptation whereas OP thwarts it by causing negative affect and rigid persistence. Results from four studies involving more than 900 participants from different populations supported the proposed conceptualization.     

Processing emotional tone from speech in Parkinson’s disease: A role for the basal ganglia

In this study, individuals with Parkinson's disease were tested as a model for basal ganglia dysfunction to infer how these structures contribute to the processing of emotional speech tone (emotional prosody). Nondemented individuals with and without Parkinson's disease (n = 21/group) completed neuropsychological tests and tasks that required them to process the meaning of emotional prosody in various ways (discrimination, identification, emotional feature rating). Individuals with basal ganglia disease exhibited abnormally reduced sensitivity to the emotional significance of prosody in a range of contexts, a deficit that could not be attributed to changes in mood, emotional-symbolic processing, or estimated frontal lobe cognitive resource limitations in most conditions. On the basis of these and broader findings in the literature, it is argued that the basal ganglia provide a critical mechanism for reinforcing the behavioral significance of prosodic patterns and other temporal representations derived from cue sequences (Lieberman, 2000), facilitating cortical elaboration of these events.     

Desensitization of postsynaptic glutamate receptors contributes to high-frequency homosynaptic depression of aplysia sensorimotor connections

Withdrawal reflexes of Aplysia are mediated in part by a monosynaptic circuit of sensory (SN) and motor (MN) neurons. A brief high-frequency burst of spikes in the SN produces excitatory postsynaptic potentials (EPSPs) that rapidly decrease in amplitude during the burst of activity. It is generally believed that this and other (i.e., low-frequency) forms of homosynaptic depression are entirely caused by presynaptic mechanisms (e.g., depletion of releasable transmitter). The present study examines the contribution that desensitization of postsynaptic glutamate receptors makes to homosynaptic depression. Bath application of cyclothiazide, an agent that reduces desensitization of non-NMDA glutamate receptors, reduced high-, but not low-frequency synaptic depression. Thus, a postsynaptic mechanism, desensitization of glutamate receptors, can also contribute to homosynaptic depression of sensorimotor synapses.     

Interpersonal and noninterpersonal interactions, interpersonal motives, and the effect of frustrated motives

A new circumplex model of interpersonal interaction emphasizes the motives that drive interpersonal behaviors and the negative affect (such as anger) that occurs when a strongly activated motive is frustrated. This study examined the model experimentally by varying conditions designed to activate and frustrate interpersonal motives. One hundred twenty-nine students engaged in text-based discussions using a computer. Three factors were varied: (a) activation of interpersonal motives--participants believed the interaction was interpersonal (with a human) or noninterpersonal (with a computer); (b) individual differences in motive activation--assertive and nonassertive participants were compared (strong vs. weak motive to influence others); and (c) level of frustration of activated motives--the "partner's" messages contained dominating or nondominating language. Participants who believed their interaction was interpersonal produced more interpersonal behaviors of various types. Assertive participants who interacted with a dominating and apparently human partner produced a disproportionate amount of hostility, indicating anger ascribed to frustrated motives.     

Gender influences as an impediment to knowledge sharing: when men and women fail to seek peer feedback

Little research has considered how work team characteristics influence feedback-seeking behavior among team members. The authors' aim in this research was to identify central sources of influence on feedback-seeking behavior in a mixed-gender context. They placed men and women in work groups of varying gender composition. The participants then participated in a gender-biased (perceived as either male-oriented or female-oriented) negotiation exercise. Findings indicated that the gender of the participant, the team's gender composition, and the gender orientation of the task influenced feedback-seeking behavior among team members.