Reinforcer value may change within experimental sessions

Large and systematic changes in response rates often occur within sessions during operant conditioning procedures. In the present experiment, we asked whether the value of the reinforcer that supports responding also changes within sessions. Pigeons pecked a key for mixed grain available throughout the session. Occasionally, wheat was also provided for pecking a second key. The ratio of the rates of responding for mixed grain and wheat, a frequently used measure of relative reinforcer value, changed significantly within sessions when mixed grain was provided at high, but not at low, rates. Habituation to the reinforcer provides the most likely explanation for these changes in reinforcer value. Eventually, habituation may provide a unified explanation for the within-session changes in behavior that occur when many species of subjects respond on a wide variety of tasks.     

Patterns of responding within sessions.

Rates of responding changed systematically across sessions for rats pressing levers and keys and for pigeons pressing treadles and pecking keys. A bitonic function in which response rates increased and then decreased across sessions was the most common finding, although an increase in responding also occurred alone. The change in response rate was usually large. The function relating responding to time in session had the following general characteristics: It appeared early in training, and further experience moved and reduced its peak; it was flatter for longer sessions; and it was flatter, more symmetrical, and peaked later for lower than for higher rates of reinforcement. Factors related to reinforcement exerted more control over the location of the peak rate of responding and the steepness of the decline in response rates than did factors related to responding. These within-session changes in response rates have fundamental theoretical and methodological implications.     

Group sessions for postgraduate students

Three group sessions were run for postgraduate students. These showed that the students wanted a close personal relationship with their supervisors, and that they often had little idea of what their research work involved. The students were shocked by the difference between their own attitudes and the supervisors'. Simple group work did much to help.     

One vs five sessions of exposure and five sessions of cognitive therapy in the treatment of claustrophobia

Forty-six patients fulfilling the DSM-IV criteria for claustrophobia were assessed with behavioral, physiological, and self-report measures. They were randomly assigned to four conditions: (1) one-session (E1); or (2) five-sessions of exposure (E5); (3) five-sessions of cognitive therapy (C5); and (4) Wait-list for 5 weeks. The first condition consisted of a single 3 h session of massed exposure, and condition 2 and 3 of 5 h of gradual treatment, which was done individually by very experienced therapists. The results showed that treatment was significantly better than the wait-list condition, and the three treatments did equally well with no differences between them. At post-treatment 79% of treatment patients vs 18% of the wait-list controls had improved to a clinically significant extent. When the three treatments were compared 80% in the E1-group, 81% in the E5-group, and 79% in the C5-group were clinically improved. At the 1 year follow-up the corresponding figures were 100%, 81%, and 93%, respectively. The implications of these results are discussed.     

A system for recording family sessions

A diagrammatic technique for recording family sessions is presented. The Interaction Chronogram is a visual display system originally devised for use in group psychotherapy by Cox, but can be modified for work with families. The system permits a family session to be summarized diagrammatically and aids review of a family's treatment. A 'diagnostic' and treatment session with one family is presented to illustrate the system's use.     

Predictive minds in Ouija board sessions

Phenomenology and the Cognitive Sciences - Ouija board sessions are illustrious examples of how subjective feelings of control – the Sense of Agency (SoA) - can be manipulated in real life...     

An investigation of the differential-outcomes effect within sessions

The differential-outcomes effect is manifest as more accurate performance of a delayed conditional discrimination when alternative choice responses are followed by different reinforcers than when they are followed by the same reinforcer. In Experiment 1, a differential-outcomes effect was demonstrated within sessions by signaling the duration of food access for correct responses with stimuli appearing in conjunction with the sample stimuli. The delayed matching-to-sample performance of 5 pigeons was more accurate when green choice responses (matching a green sample) were followed by 3.5-s food access and red choice responses (matching a red sample) were followed by 0.5-s food access (different-outcome trials) than when the correct choice responses were both followed by 1.5-s reinforcers (same-outcome trials). In Experiment 2, the acquisition of this differential-outcomes effect was characterized by a progressive decrease in rate of forgetting on different-outcome trials and no change in rate of forgetting on same-outcome trials. In addition, accuracy at the shortest delay intervals for both different-outcome and same-outcome trials increased over acquisition, but to a greater extent for different-outcome trials. These data suggest that both memorial and attentional (time-dependent and time-independent) factors contribute to the differential-outcomes effect.     

Efficacy of booster sessions after training in assertiveness

28 subjects participated in a 6-wk. assertion training program. Of these, 22 remained in the study for a 6-mo. follow-up period, during which half received monthly booster sessions and half did not. Assignment to the booster and no-booster groups was random, with the qualification that subjects were equated on trait anxiety before training in assertiveness. Subjects filled out the Gambrill-Richey Assertion Inventory, the Spielberger State-Trait Anxiety Inventory, and the Zung Self-rating Depression Scale before the 6-wk. assertion training, after this program, at a 3-mo. follow-up, and at a 6-mo. follow-up. It was hypothesized that the booster group would exhibit significant superiority on these measures at the 3-mo. and 6-mo. follow-ups. On all measures both groups significantly improved from before to after the training program with good maintenance throughout the follow-ups. There were no differences between the booster and no-booster groups on the measures of assertiveness and anxiety. However, there was a significant interaction for the depression scores when the booster and no-booster groups were compared from posttreatment to 6-mo. follow-up. The depression scores of subjects in the booster group were lower than the depression scores of subjects in the no-booster group at the 6-mo. follow-up. These results were discussed with suggestions for further research.     

Finger tapping: effects of trials and sessions

18 normal, self-reported dextral subjects (9 men, 9 women) were assessed with a Halstead Manual Finger Tapping device, with 10 trials per hand for 10 consecutive wk. The test-retest reliability of the 10-trial average between the 10 sessions averaged .94 for men and .86 for women, for both preferred and nonpreferred hands. There were no statistically significant effects of increases in performance over sessions or effects of fatigue over trials for either sex or hand. There were, however, significant increases over trials for men for both preferred and nonpreferred hands.     

Timing divided attention

Visual attention can be divided over multiple objects or locations. However, there is no single theoretical framework within which the effects of dividing attention can be interpreted. In order to develop such a model, here we manipulated the stage of visual processing at which attention was divided, while simultaneously probing the costs of dividing attention on two dimensions. We show that dividing attention incurs dissociable time and precision costs, which depend on whether attention is divided during monitoring or during access. Dividing attention during monitoring resulted in progressively delayed access to attended locations as additional locations were monitored, as well as a one-off precision cost. When dividing attention during access, time costs were systematically lower at one of the accessed locations than at the other, indicating that divided attention during access, in fact, involves rapid sequential allocation of undivided attention. We propose a model in which divided attention is understood as the simultaneous parallel preparation and subsequent sequential execution of multiple shifts of undivided attention. This interpretation has the potential to bring together diverse findings from both the divided-attention and saccade preparation literature and provides a framework within which to integrate the broad spectrum of divided-attention methodologies.     

The Timing of Feminism

Is history a category of reason, or is reason a category of history? These opposing questions have divided the structuralist from the materialist—but neither question is wrong. Analysis of the logic of oppositions challenges feminism, in particular, to find a logic—and a poetics—in which to render its values without historical or theoretical naivete. I explore the question of the timing of feminism through Julia Kristeva and Luce Irigaray.     

Response Timing Variability

A detailed kinematic and electromyographic (EMG) analysis of single degree of freedom timing responses is reported to (a) determine the coherence of kinematic and EMG variability to the reduced timing error variability exhibited with amplitude increments within a given criterion movement time and (b) understand the temporal organization of various movement parameters in simple responses. The data reveal that the variability of kinematic (time to peak acceleration, duration of acceleration phase, time to peak deceleration) and EMG (duration of agonist burst, duration of antagonist burst, time to antagonist burst) timing parameters decreased with increments of average velocity in a manner consistent with the variable timing error. In addition, the coefficient of variation for peak acceleration, peak deceleration, and integrated EMG of the agonist burst followed the same trend. Increasing average movement velocity also led to decreases in premotor and motor reaction times. Overall, the findings suggest a strong coherence between the variability of response outcome, kinematic, and EMG parameters.