Neurochemical changes correlated with behavior maintained under fixed-interval and fixed-ratio schedules of reinforcement.

Key pecking of 4 pigeons was maintained under a multiple 3-min fixed-interval, 30-response fixed-ratio schedule of food presentation. Only one schedule was in effect during an experimental session, and each was correlated with a different keylight stimulus and location (left vs. right). The different schedule components alternated across days or weeks. Cerebrospinal fluid was collected from chronically implanted intracerebroventricular cannulae following sessions with the different schedules, as well as following sessions in which reinforcement was withheld (extinction), when response-independent food was delivered, and when the experimental chamber was dark and there were no scheduled events. Metabolites of the neurotransmitters serotonin, norepinephrine, and dopamine were assayed in cerebrospinal fluid using high-performance liquid chromatography with electrochemical detection. Compared to the fixed-ratio condition, responding maintained under the fixed-interval schedule resulted in consistently higher levels of the serotonin metabolite 5-hydroxyindoleacetic acid and of the dopamine metabolite homovanillic acid in all pigeons. Levels of 3-methoxy-4-hydroxyphenylethylene glycol, a metabolite of norepinephrine, and dihydroxyphenylacetic acid, another dopamine metabolite, were also higher in 3 of the 4 pigeons following exposure to the fixed-interval schedules when compared to levels of these metabolites after exposure to the fixed-ratio schedule. Extinction of fixed-ratio responding resulted in large increases in 5-hydroxyindoleacetic acid compared to levels of this metabolite under the fixed-ratio schedule, whereas this serotonin metabolite decreased during extinction of responding under the fixed-interval schedule. Control procedures suggested that the neurochemical changes were not related to the rate of responding but were a function of the specific experimental conditions. Distinctive neurochemical changes that accompany schedule-controlled responding show the sensitivity of the neurochemical environment to behavioral contingencies and demonstrate further the profound impact that such contingencies have on biobehavioral processes.     

Visually based amendments of aiming movements: a reappraisal of Christina (1970).

The present paper examines the processing of visual information during the initial and corrective phases of an aimed movement. Visual processing in the corrective phase is related to the nature of the error in the initial phase. By producing a deliberate error, the system knows the approximate amplitude and direction in advance, allowing for the preprogramming of the corrective response. The final response, however, awaits visual confirmation with a processing time on the order of 130 msec. This strategy is feasible only if the variability in the initial response is constrained, which is the role of an additional very rapid feedback loop (70 to 100 msec.).     

Strategies to motivate helpless and mastery-oriented children: The effect of gender-based expectancies

Five studies examined potential determinants of gender differences in helplessness by investigating two major steps in the expectancy confirmation process. The first step, i.e., an examination of gender-based expectancies, was addressed in three studies in which subjects (parents and college students) read vignettes that included either masculine or feminine sex-linked tasks performed by helpless and mastery-oriented children. We hypothesized that across tasks subjects would consider a “helpless” approach toward achievement as stereotypic of girls and “mastery-oriented” behavior as stereotypic of boys. The next step of the expectancy confirmation process, and central question addressed here, centered on the proposed differential treatment prescribed for children who performed inadequately on an academic activity, depending on whether these children's behaviors were consistent or inconsistent with stereotypic expectations. The pattern of data obtained generally supported hypotheses that (1) under conditions in which children's behavior confirmed expectancies, i.e., girls acting helpless and boys showing mastery-oriented behaviors, supportive responses would be prescribed, whereas (2) when children's behavior violated expectancies, i.e., girls acting in a mastery-oriented manner and boys acting in a helpless manner, more controlling techniques would be used. These findings are discussed in terms of consequences of use of these different strategies to remedy helpless behaviors in children.     

Overt activity during conditioned suppression: a search for punishment artifacts

Pigeons, previously trained to peck a key (using food as the reinforcer), were permitted unlimited access to food and, concurrently, key pecking was allowed to go unreinforced until all pecking ceased. A tone ending with electrical shock was then repeatedly presented in an effort to establish the tone as a potentially suppressing stimulus. When key pecking was later reestablished, tone presentation (without shock) sharply reduced the rate of pecks. At selected points throughout the experiment, special observation procedures supplemented the recordings of key pecks and provided detailed fine-grain protocols of the birds' overt movements during the periods before, during, and after tone presentations. Results indicated that neither punishment of key pecks nor punishment of other overt movements was a necessary precursor to the conditioned suppression observed in the final stage. As such, the findings support interpretations of conditioned suppression that characterize the phenomenon as reflecting a conditioned emotional reaction that either directly or indirectly inhibits overt activity.     

Self-Efficacy and Training for Strength in Adolescent Girls1

To test the hypothesis that a gain in self-efficacy about strength training could generalize to other areas of life and positively affect self-esteem, untrained adolescent female volunteers were tested before and after participation in 12 weeks of strength training and compared with nonactive and mildly active volunteer controls. Pretest-posttest results for the treatment group showed improvement in strength (+40%), weight training efficacy, confrontation efficacy, and total efficacy summed over 11 tasks. There were related positive changes in perceived physical ability, physical self-presentation confidence, and general effectiveness in life. The treatment group improved posttest over controls on all these variables; controls did not change or worsened. These findings offer preliminary support that weight training for strength can improve confidence about a variety of life tasks in adolescent girls and could provide the basis for new modalities of therapy for low self-esteem.     

Learning of a complex arithmetic skill in amnesia: evidence for a dissociation between compilation and production

Two patients with severe amnesia following rupture of anterior communicating artery aneurysms were able to learn a complex algorithm for mentally squaring two-digit numbers. Although both patients learned the algorithm at a similar rate, one patient's improvement was accounted for by savings in the steps of the algorithm. The other patient, however, showed little improvement in the steps while performance of the whole algorithm improved dramatically. Neither patient showed savings in the Hebb Digit Span procedure. The results suggested a dissociation between amnesics in their capacity to learn the constituent "productions" or steps of a skill and their capacity to organize those productions into a single coherent act.     

Use of the maximal-operant principle to motivate children's intrinsic interest

The present research examined the hypothesis that in contrast to theory and research indicating that tangible reward decreases subsequent interest in enjoyable academic activities, rewards are perceived by adults as effective techniques to maximize long- and short-term subsequent interest for academic tasks of both high and low initial interest level. The results of our first three studies demonstrated that college students and parents view tangible reward as more effective than other less controlling techniques to enhance intrinsic motivation and value rewards more for intrinsically interesting academic behaviors in comparison with others (e.g., prosocial behaviors). Our fourth study supported the hypothesis that adults do not subscribe to the minimal-sufficiency analysis of increasing intrinsic motivation but prefer a maximal-operant principle in which the likelihood of producing long-term interest in academic tasks is assumed to vary positively with the size of a reward. Our fifth and sixth studies investigated illusory correlation as one mechanism that may perpetuate beliefs about the assumed positive relation between tangible reward and intrinsic interest in academic tasks.