Sensitization and habituation of motivated behavior in overweight and non-overweight children

The rate of habituation to food is inversely related to energy intake, and overweight children may habituate slower to food and consume more energy. This study compared patterns of sensitization, as defined by an initial increase in operant or motivated responding for food, and habituation, defined by gradual reduction in responding, for macaroni and cheese and pizza in overweight and non-overweight 8- to 12-year-old children. Non-overweight children habituated faster to both foods than overweight children (p = .03). All children recovered motivated responding for a new food (chocolate). Overweight children consumed more energy than non-overweight children (p = .0004). Children who showed a sensitization in responding consumed more food (p = .001), and sensitization moderated the effect of overweight on habituation, with slower habituation for overweight children who sensitized (p < .001). This study replicates previous data on overweight/non-overweight differences in habituation of food and energy intake, and provides new information that individual differences in sensitization and habituation of motivated responding to obtain food may be associated with a sustained motivation to eat, resulting in greater energy intake.     

An analysis of coordinated responding of pigeons

Experimental analyses of coordinated responding (i.e., cooperation) have been derived from a procedure described by Skinner (1962) in which reinforcers were delivered to a pair of subjects (a dyad) if both responded within a short interval, thus satisfying a coordination contingency. Although it has been suggested that this contingency enhances rates of temporally coordinated responding, limitations of past experiments have raised questions concerning this conclusion. The present experiments addressed some of these limitations by holding the schedule of reinforcement (Experiment 1: fixed ratio 1; Experiment 2; variable interval 20 s) constant across phases and between dyad members and by varying, in different conditions, the number of response keys (one to three) across which coordination could occur. Greater percentages of coordinated responding occurred under the coordinated-reinforcement phases than under independent-reinforcement phases in most conditions. The one exception during the one-key condition of Experiment 1 appeared to be a consequence of variability introduced by the independent-reinforcement phase procedure. Furthermore, coordination percentages decreased with increasing response options under both schedules. These results confirm and extend the finding that coordination contingencies control higher rates of temporally coordinated responding than independent-reinforcement contingencies do.     

Method effects due to social desirability as a parsimonious explanation of the deviation from unidimensionality in LOT-R scores

Dispositional optimism measured by the Life Orientation Test (Revised; LOT-R, Scheier et al., 1994) was originally proposed as a unidimensional construct pertaining to individual differences in positive outcome expectancies. However, factor analytic research has suggested two separate “optimism” and “pessimism” factors associated with positively and negatively worded items respectively. Using confirmatory factor analysis with data from N = 658 students it is shown that a general optimism model with method effects of the positively worded items fits even better than the “optimism–pessimism” model in terms of the AIC statistic, which accounts for both model parsimony and model fit. Furthermore, an attempt is made to explain the method effects by social desirability: impression management, one of two components of socially desirable responding, correlates significantly with the method factor whereas the other component, self-deceptive enhancement, is related to the general optimism factor. Thus it is shown that the deviation from unidimensionality of observed scores does not imply deviation from unidimensionality of optimism when method effects are incorporated in the model.     

THE EFFECTS OF RESPONSE CARDS ON STUDENT AND TEACHER BEHAVIOR DURING VOCABULARY INSTRUCTION

The use of response cards during whole‐class English vocabulary instruction was evaluated. Five low‐participating students were observed during hand‐raising conditions and response‐card conditions to observe the effects of response cards on student responding and test scores and teacher questions and feedback. Responding and test scores were higher for all targeted students in the response‐card condition. The teacher asked a similar number of questions in both conditions; however, she provided more feedback in the response‐card condition.     

Within-session changes in responding during concurrent schedules with different reinforcers in the components.

Rats and pigeons responded on several concurrent schedules that provided different reinforcers in the two components (food and water for rats, Experiment 1; wheat and mixed grain for pigeons, Experiment 2). The rate of responding and the time spent responding on each component usually changed within the session. The within-session changes in response rates and time spent responding usually followed different patterns for the two components of a concurrent schedule. For most subjects, the bias and sensitivity to reinforcement parameters of the generalized matching law, as well as the percentage of the variance accounted for, decreased within the session. Negative sensitivity parameters were sometimes found late in the session for the concurrent food-water schedules. These results imply that within-session changes in responding could cause problems for assessing the validity of quantitative theories of concurrent-schedule responding when the components provide different reinforcers. They question changes in a general motivational state, such as arousal, as a complete explanation for within-session changes in responding. The results are compatible with satiation for, or sensitization-habituation to, the reinforcers as explanations.     

The Importance of Overt Responding in Programmed Instruction Even with Added Incentives for Learning

Among the fundamental tenets of programmed instruction is the requirement of overt responding. Past research has not determined when this tenet holds true. We systematically replicated the work of Tudor (1995) by showing that overt responding in computer-based instruction improves learning, even when there is an incentive that might be thought to improve learning enough to mask the effect of overt responding. Subjects were exposed to both read-only and overt-response materials. One group received course-related, bonus points based on posttest performance, whereas the other group received points simply for participation. Within-subject comparison showed greater performance increases when overt responding was required, regardless of the point incentive. No significant differences were found between groups.     

Ratio responding as a function of concurrent avoidance schedules, yoked shocks, and ratio value

Fixed-ratio food-reinforced responding in rats was studied alone and with concurrent shock avoidance or with concurrent response-independent shocks matched to those that occurred in the avoidance condition. Under each condition, fixed-ratio size was increased over successive daily sessions. Fixed-ratio response rate generally passed through a maximum as a function of fixed-ratio size. Decreased fixed-ratio responding at values beyond the maximum occurred when (1) the time to complete a fixed ratio approximated the response-shock interval of the avoidance schedule, (2) the shock rate increased, and/or (3) the ratio requirements were so high that ratio strain occurred. Avoidance rates decreased slightly as fixed-ratio size increased.     

DISCRIMINATIVE CONTROL OF THERAPISTS' PERFORMANCE1

In order to examine therapists' discriminative responding to normal and idiosyncratic patient responses, naive subjects were presented with a simulated “patient” for treatment. The subjects were made to believe they were reinforcing normal verbalizations emitted by this patient In fact, they were listening to a tape on which normal and idiosyncratic verbalizations had been recorded. Different probabilities of normal and idiosyncratic “patient” verbalizations could be presented to the subjects by means of a digital programming unit. In one of a number of conditions, the subjects' accurate reinforcing responses were followed by an increased probability of the patient's normal verbalizations. Accurate reinforcing responses emitted by the subjects were brought under the control of normal and idiosyncratic patient responses, by use of contingent feedback, change in patient responding, and monetary reinforcers. When the patient's normal verbalizations increased in probability, so did the subjects' accurate reinforcing responses following the patient's normal verbalizations, and to a lesser degree, the subjects' inaccurate reinforcing responses following the patient's idiosyncratic verbalizations. When the patient's idiosyncratic verbalizations increased in probability, the subjects' accurate and inaccurate reinforcing responses decreased in probability. The clinical implications of these tendencies are discussed.     

Elicited responding to signals for reinforcement: the effects of overall versus local changes in reinforcement probability

Pigeons were studied on a three-component multiple schedule where all reinforcement was independent of responding. Two components were cued by different keylights and were associated with different rates of reinforcement. The third was always a no-key period associated with extinction. After a few sessions, pecking was elicited by the keylights signalling the reinforcement and continued to be maintained indefinitely. The duration and sequence of the three components were varied to determine if the primary controlling variable was differences in the overall probability of reinforcement, or if it was the immediate change in reinforcement signalled by the onset and/or offset of the stimulus. Both variables were found to control behavior. When 30-sec components were used, the primary controlling variable was the overall probability of reinforcement, but when 3-min components were used, overall probability had little effect. Control by local changes in reinforcement also occurred, although the type of local control varied both across subjects and experimental conditions. Some behaviors were controlled more by the change in reinforcement signalled by the onset of the stimulus, while others were controlled more by the change signalled by the offset of the stimulus.