Within-Session Patterns of Pigeons'' General Activity

The study investigates the idea that within-session changes in responding are produced by arousal and satiation. General activity, measured by the displacement of floor panels, was used as an index of these variables. In Experiment 1, pigeons pecked a key on a simple variable-interval schedule and general activity was also recorded. In Experiment 2, pigeons received response-independent reinforcers. In Experiment 3, the pigeons' general activity was reinforced on a variable-interval schedule. Although significant within-session changes in operant key pecking were observed in Experiment 1, within-session changes in general activity were seldom observed in either Experiment 1 or Experiment 2. Significant within-session changes in general activity were observed in Experiment 3, when activity was the operant. The present results can potentially be explained by arousal and satiation. However, the predictive power of this explanation is severely limited. Regardless of whether one accepts arousal and satiation as the theoretical explanation for within-session changes in responding, the present results suggest that aspects of the response–reinforcer relation may determine the within-session pattern of responding.     

Within-Session Changes in Adjunctive and Instrumental Responding

Rats pressed levers for food delivered by several fixed interval schedules. A drinking spout or running wheel was also available during some conditions, but not during others. The rate of lever pressing, drinking and running often changed within experimental sessions. The within-session patterns of lever pressing did not differ when drinking or running was available and when it was not. The correlation between the amount of lever pressing and the amount of drinking or running at a particular time in the session was inconsistently positive or negative. Finding within-session changes in responding for adjunctive behaviors implies that the factors that produce these changes are present for both adjunctive and instrumental behavior. Finding inconsistent correlations between instrumental responding and adjunctive behaviors questions arousal and interference from adjunctive behaviors as explanations for within-session changes in instrumental responding.     

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.     

Evaluating a treatment without extinction for elopement maintained by access to stereotypy

Elopement is a common and potentially dangerous form of problem behavior. Results of a functional analysis found that the elopement of a child with autism was maintained by access to stereotypy in the form of door play. We implemented functional communication training and contingency-based delays dependent on the absence of elopement and increased the amount of time the participant waited prior to engaging in stereotypy. We also conducted treatment-extension probes, with the participant waiting up to 10 min without elopement.     

Parent or community: Where do 20-month-olds exposed to two accents acquire their representation of words?

The recognition of familiar words was evaluated in 20-month-old children raised in a rhotic accent environment to parents that had either rhotic or non-rhotic accents. Using an Intermodal Preferential Looking task children were presented with familiar objects (e.g. 'bird') named in their rhotic or non-rhotic form. Children were only able to identify familiar words pronounced in a rhotic accent, irrespective of their parents' accent. This suggests that it is the local community rather than parental input that determines accent preference in the early stages of acquisition. Consequences for the architecture of the early lexicon and for models of word learning are discussed.     

Family-focused cognitive behaviour therapy versus psycho-education for adolescents with chronic fatigue syndrome: Long-term follow-up of an RCT

The aim of this study was to investigate the long term efficacy of family-focused cognitive behaviour therapy (CBT) compared with psycho-education in improving school attendance and other secondary outcomes in adolescents with chronic fatigue syndrome (CFS). A 24 month follow-up of a randomised controlled trial was carried out. Participants received either 13 one-hour sessions of family-focused CBT or four one-hour sessions of psycho-education. Forty-four participants took part in the follow-up study. The proportion of participants reporting at least 70% school attendance (the primary outcome) at 24 months was 90% in CBT group and 84% in psycho-education group; the difference between the groups was not statistically significant (OR = 1.29, p = 0.80). The proportion of adolescents who had recovered in the family-focused CBT group was 79% compared with 64% in the psycho-education, according to a definition including fatigue and school attendance. This difference was not statistically significant (Fisher's exact test, p = 0.34). Family-focused CBT was associated with significantly better emotional and behavioural adjustment at 24 month follow-up compared to psycho-education, as reported by both adolescents (F = 6.49, p = 0.02) and parents (F = 4.52, P = 0.04). Impairment significantly decreased in both groups between six and 24 month follow-ups, with no significant group difference in improvement over this period. Gains previously observed for other secondary outcomes at six month follow-up were maintained at 24 month follow-up with no further significant improvement or group differences in improvement. In conclusion, gains achieved by adolescents with CFS who had undertaken family-focused CBT and psycho-education generally continued or were maintained at two-year follow-up. The exception was that family-focused CBT was associated with maintained improvements in emotional and behavioural difficulties whereas psycho-education was associated with deterioration in these outcomes between six and 24-month follow-up.     

Group Dynamics in Physical Activity Promotion: What works?

Over the past 20 years group dynamics‐based interventions have been used to successfully increase physical activity. However, the literature is less clear on the underlying mechanisms of effectiveness. That is, what makes these group dynamics interventions work? We conducted a systematic review to identify studies that used different group dynamics strategies to promote physical activity. Seventeen studies were identified and were coded by two raters to determine the degree to which group dynamics strategies were used, the format of the programs, and any analytic procedures used to determine the causal mechanisms underlying intervention effectiveness. The results of the coding indicated that while there is no standard package of group dynamics strategies being applied across the literature‐ and regardless of the breadth of the underlying theory or the structure of the programs‐ the effect on physical activity is robust. However, few studies explicitly measured potential causal mechanisms and even fewer completed the necessary analysis to detect mediation. We concluded that future research on developing a unified theory for group dynamics with appropriate measurement tools is necessary to further enhance the effects of group dynamics on physical activity promotion.