Effects of free food deliveries and temporal contiguity on choice under concurrent-chain schedules

Eight pigeons responded in a concurrent chain with variable-interval (VI) 10-sec and VI 20-sec terminal links. Free food deliveries were then added to the initial links according to a variable-time (VT) 20-sec schedule in two conditions that differed in terms of whether a differential reinforcement of other (DRO) contingency was also arranged, which ensured that those deliveries could not occur within 2-sec of a response. Preference for the VI 10-sec terminal link increased when VT food was added, but not when the DRO contingency was operative, showing that free food deliveries affected preference only when those deliveries could be temporally contiguous with choice responding. This finding suggests that Mazur’s (2003) report of increased preference with added VT food, replicated here, was due to adventitious reinforcement. Current models for behavioral choice are limited because they are based entirely on temporal relations between stimuli and reinforcers and fail to take into account response-reinforcer contiguity.     

Why recall our highs and lows: relations between memory functions, age, and well-being

This study examined whether positive and negative memories (life story high and low points) were differentially used for reminiscence functions concerning self and social aspects of reminiscing, and relations between function use and well-being in two age groups. Life story high and low points were collected from a sample of emerging (n =56) and older (n =55) adults, as well as a measure of the use of these memories for the self-functions of death preparation, identity, and problem solving, and the social functions of conversation and teach/inform, and a measure of psychological well-being. Memories were also coded for whether or not they contained a redemptive narrative structure (from emotionally negative to emotionally positive). Results showed that the endorsement of reminiscence functions did differ by memory type, with high points more often endorsed for the functions of identity, teach/inform, and conversation than low points. These main effects were qualified by memory type x age interactions. The use of these functions for each kind of memory was also related to well-being, but differentially for older and younger people, and redemptive sequencing was especially important to the well-being of the younger group. Findings are discussed in terms of the importance of different emotional memories for self and well-being at different points in the lifespan.     

Seasonal variation in pigeon body weight and delayed matching-to-sample performance

The weights of 5 pigeons with free access to food, monitored over 3 calendar years in the laboratory, were found to fluctuate with season. All pigeons were at their heaviest in the winter and were lightest in the summer. Five different pigeons performed a standard delayed matching-to-sample task for 44 weeks from January to November. Their weights were held at 85% of their summer free-feeding weights, making their predicted deprivation level higher in the winter relative to predicted winter free-feeding weights. Slopes of forgetting functions fit to weekly response totals for each pigeon were shallower in winter, showing an improvement in accuracy with longer delays. Thus, delayed matching-to-sample performance may have been affected by the practice of maintaining the pigeons at a constant body weight throughout the calendar year.     

Silent talker: a new computer‐based system for the analysis of facial cues to deception

This paper presents the development of a computerised, non‐invasive psychological profiling system, ‘Silent Talker’, for the analysis of non‐verbal behaviour. Nonverbal signals hold rich information about mental, behavioural and/or physical states. Previous attempts to extract individual signals and to classify an overall behaviour have been time‐consuming, costly, biased, error‐prone and complex. Silent Talker overcomes these problems by the use of Artificial Neural Networks. The testing and validation of the system was undertaken by detecting processes associated with ‘deception’ and ‘truth’. In a simulated theft scenario thirty‐nine participants ‘stole’ (or didn't) money, and were interviewed about its location. Silent Talker was able to detect different behaviour patterns indicative of ‘deception’ and ‘truth’ significantly above chance. For example, when 15 European men had no prior knowledge of the exact questions, 74% of individual responses ( p < 0.001) and 80% ( p = 0.035) of interviews were classified correctly. Copyright © 2006 John Wiley & Sons, Ltd.     

Case report of stuttering acquired in association with phenytoin use for post-head-injury seizures

Previous research indicates that stuttering and deficits in motor performance may be associated with the use of phenytoin (Dilantin). The present report concerns a case of stuttering acquired in association with phenytoin use for post-head-injury seizures. The extent and nature of dysfluencies and the motor performance of speech and nonspeech muscle systems were evaluated over an extended period during which changes in anticonvulsant medication were made. Reductions in dysfluency levels and improved motor performance were observed following a medication change from phenytoin to carbamazepine. Performance on tests assessing nonmotor functions, such as memory and attention, was equivalent before and after the medication change. The apparent association between dysfluency levels, motor performance deficits, and phenytoin suggest that in the present case stuttering resulted in part from a general impairment in motor control.     

Training for the production of novel timing movements: Contextual considerations

Summary The present study represented an attempt to determine the extent to which transfer performance on a novel timing task is influenced by contextual similarity (i.e., similar instructions, task requirements, etc.) between training and transfer phases of performance. All subjects were given trials on a task which involved a linear ballistic arm movement. The length of the movement was defined as the distance between a start button and a hinged target, which was knocked over by the subject at the end of the response. During training subjects attempted to produce their movements in a time of 550 ms and were given knowledge of results regarding timing error after each trial. During transfer trials a 300 ms movement time was attempted and no knowledge of results was given. Context was defined by the number of different movement distances performed during training and transfer. Half of the subjects received training trials with a single distance (constant context) while the other half received an equal number of trials with each of three distances (varied context). During the transfer stage of the experiment, subjects either performed in the same movement distance context experienced during training (i.e., constant to constant; varied to varied) or in the opposite context (i.e., constant to varied; varied to constant). The results of the transfer analysis suggested that similariy of context between training and transfer phases of performance was not crucial to the accurate production of a novel closed-timing movement. Implications of the present results for recent theories of memory development are discussed.     

Resistance to change and the law of effect

Three experiments using multiple schedules of reinforcement explored the implications of resistance-to-change findings for the response-reinforcer relation described by the law of effect, using both steady-state responding and responding recorded in the first few sessions of conditions. In Experiment 1, when response-independent reinforcement was increased during a third component, response rate in Components 1 and 2 decreased. This response-rate reduction was proportionately greater in a component in which reinforcer magnitude was small (2-s access to wheat) than in the component in which it was large (6-s access to wheat). However, when reinforcer rates in the two components were varied together in Experiments 2 and 3, response-rate change was the same regardless of the magnitude of reinforcers used in the two components, so that sensitivity of response rates to reinforcer rates (Experiment 2) and of response-rate ratios to reinforcer-rate ratios (Experiment 3) was unaffected by the magnitude of the reinforcers. Therefore, the principles determining resistance to change, described by behavioral momentum theory, seem not to apply when the source of behavior change is the variation of reinforcement contingencies that maintain the behavior. The use of extinction as a manipulation to study resistance to change is questioned.