Sensitivity of time allocation to an overall reinforcer rate feedback function in concurrent interval schedules

Six pigeons were trained on concurrent variable-interval schedules in which feedback functions arranged that the overall reinforcer rate either (a) was independent of preference, (b) decreased with increasing absolute preference, or (c) increased with increasing absolute preference. In Experiment 1, the reinforcer rate in an interreinforcement interval was determined by the absolute time-allocation ratio in the previous interval. When arranged reinforcer ratios were varied, there was no evidence of control over preference by overall reinforcer rate. In Experiment 2, the feedback function arranged that reinforcer rates were an inverse function of absolute preference, and window durations were fixed times. In Phase 1, using schedules that provided a four-to-one reinforcer ratio, the window duration was decreased from 20 s to 5 s over four conditions. Then, in Phases 2 and 3, the arranged reinforcer ratios were varied. In Phase 2, the reinforcer rate in the current 5-s time window was determined by preference in the previous 5-s window, and in Phase 3, the window durations were 20 s. Again, there was no indication of control by obtained overall reinforcer rate. These data call into question theories that suggest that the process underlying matching is one of maximizing overall reinforcer rates, or that preference in concurrent aperiodic schedules is controlled to any extent by overall reinforcer rate. They also question the notion that concurrent-schedule preference is controlled by molecular maximizing.     

Discrete and continuous measures of dimensional stimulus control

In two sets of experiments, we examined dimensional stimulus control of pigeons' responses to a visual flicker-rate continuum. In the first experiment, responses to a single key were reinforced periodically during stimuli from one half of the stimulus continuum, and responses during other stimuli were extinguished. In the second experiment, two response keys were simultaneously available, with reinforcement for each response alternative associated with different halves of the stimulus continuum. Conditions of the second experiment involved either free-operant or discrete-trial stimulus presentations. Results from these experiments show that positive dimensional contrast appeared in discrimination tasks with one or two response alternatives, but only with free-operant procedures. In addition, discrimination between stimulus classes established by differential reinforcement was assessed as accurately by continuous rate measures as by discrete response choice in the two-alternative situation. The general implication of these experiments is that response rate measures, when properly applied, may reveal sources of variation within stimulus classes, such as dimensional contrast, that are not evident with discrete measures.     

Chlordiazepoxide effects on ethanol self-administration: dependence on concurrent conditions.

Experiments examined the effects of acute doses of chlordiazepoxide upon ethanol self-administration in the rat. A concurrent-schedule procedure was used that employed choice between ethanol (5%) and a second fluid (either water or a 1% sucrose solution). When ethanol and water were the available fluids, chlordiazepoxide at doses of 15 and 20 mg/kg reduced ethanol-reinforced responding and intake, with a greater reduction occurring at the 20 mg/kg dose. However, when ethanol and sucrose were concurrently available, in many rats only the 20 mg/kg dose of chlordiazepoxide reduced ethanol-reinforced responding. The differences in dose response function occurred in most animals without large changes in the baseline ethanol-reinforced responding across the two concurrent conditions. Thus the dose-effect curve relating chlordiazepoxide and ethanol self-administration can be altered, dependent upon the nature of the concurrently available reinforcers.     

Modality-repetition and attentional effects on reflex blinking in infants and adults

The ability of a brief prepulse to inhibit reflexively elicited startle is a robust phenomenon in adults of several species but is weak or absent in infants. The possibility that afferent processing of the prepulse is inadequate in infants was tested by assessing the integrity of two other types of reflex modulation that occur in modality-specific paths, that is, attenuation by repetition of same-modality stimuli and enhancement by modality-selective attention. The reflex, measured by electromyographic activity of the muscle controlling blink, was elicited by intense light flashes or noise bursts preceded by brief acoustic or visual prepulses and delivered during attention-directing acoustic or visual foregrounds that evoked cardiac deceleration. Modality-repetition effects were evidenced by smaller peak blink magnitude and longer latency of blinking to same than to different modality pairs and did not differ as a function of age (4-month-old infants or college students). Attention effects were also seen in both infants and adults and, in accord with previous findings, were evident in magnitude for infants and latency for adults. Thus, immaturity in paths mediating these effects could not explain delayed development of prepulse inhibition. Other possibilities include delayed maturation of extrinsic inhibition or of transient-processing systems.     

自控速度的平滑滚动引导式和RSVP的文本阅读

考察了在自控速度条件下 ,显示窗口、起始速度和文本显示方式等因素对视频显示终端 (videodisplayter minals,VDT)汉语文本阅读工效的影响。结果发现 :(1)在阅读正确率上 ,VDT文本的平滑滚动引导式优于快速系列视觉呈现 (rapidserialvisualpresentation ,RSVP)方式 ;(2 )阅读速度和阅读理解成绩相互代偿 ,若注重理解正确率 ,宜采用 15 0字 /分的起始速度 ;若兼顾阅读速度 ,宜采用 75 0字 /分的起始速度 ;(3)起始速度、显示窗口和文本显示方式三者共同影响了阅读绩效 ;(4 )机控速度方式的阅读效率优于自控速度方式。     

贝叶斯推理研究综述

Kahneman 和Tversky在70年代初期发现人们在概率推理中并不遵循数学上的贝叶斯定理,常常由于忽略问题中的基础概率而对稀少事件的条件概率作出夸大的反应。此后心理学家采用文本范式和经验范式对此问题进行了大量的研究,并涌现了一些不同的理论观点,主要有启发法策略论(代表性启发法和可得性启发法)、自然抽样空间假说、频率效应论和抽样加工理论。     

Accuracy of discrimination,rate of responding,and resistance to change

Pigeons were trained on multiple schedules in which responding on a center key produced matching-to-sample trials according to the same variable-interval 30-s schedules in both components. Matching trials consisted of a vertical or tilted line sample on the center key followed by vertical and tilted comparisons on the side keys. Correct responses to comparison stimuli were reinforced with probability .80 in the rich component and .20 in the lean component. Baseline response rates and matching accuracies generally were higher in the rich component, consistent with previous research. When performance was disrupted by prefeeding, response-independent food during intercomponent intervals, intrusion of a delay between sample and comparison stimuli, or extinction, both response rates and matching accuracies generally decreased. Proportions of baseline response rate were greater in the rich component for all disrupters except delay, which had relatively small and inconsistent effects on response rate. By contrast, delay had large and consistent effects on matching accuracy, and proportions of baseline matching accuracy were greater in the rich component for all four disrupters. The dissociation of response rate and accuracy with delay reflects the localized impact of delay on matching performance. The similarity of the data for response rate and accuracy with prefeeding, response-independent food, and extinction shows that matching performance, like response rate, is more resistant to change in a rich than in a lean component. This result extends resistance to change analyses from the frequency of response emission to the degree of stimulus control, and suggests that the strength of discriminating, like the strength of responding, is positively related to rate of reinforcement.     

Transient cardiac responses to witnessing horrible events in young adult female exercisers and non-exercisers

ObjectivesIt has been proposed that regular exercisers may be less vulnerable to the effects of stress and better able to cope with aversive events than people who are sedentary, but findings have not been consistent. In the present study, physiological variables indicating specific relevant psychological processes were used to objectively assess women's responses to stressful events.Design and MethodNon-exercising (n = 56) and regularly exercising women (up to 4 h, n = 62, and more than 4 h per week, n = 50) were viewing an aversive film consisting of scenes of real injury and death, and their transient cardiac responses to sudden horrifying events happening to persons in the film were obtained, as well as changes of prefrontal-posterior coupling, measured by EEG.ResultsCompared to regularly exercising women, non-exercising women showed a clearly more pronounced second accelerative component of the transient heart rate response to the terrifying events, indicating greater sensitivity of the avoidance (defensive) motivational system and heightened sensitivity to aversive stimuli. Moreover, non-exercising women did not show the expected characteristic initial heart rate acceleration when the scene approached its fatal end, that is, more rigid responding, and EEG data indicated less susceptibility to affect-laden information at the perceptual level.ConclusionsThe findings support the notion of less adaptive coping with adverse events in sedentary compared to exercising women and add to the growing evidence suggesting a stress-buffering effect of regular exercise, therefore promoting resilience and resistance to the negative impact of stressor and trauma exposure.     

Response rate on the Adjusted Rorschach Comprehensive System (ARCS) by isiXhosa learners: a replication and extension

This study describes the response profiles of a sample of isiXhosa learners regarding to the Adjusted Rorschach Comprehensive System (ARCS) and related influences to explain the response latencies. This was a multiple case study in which six test naive high school learners (females = 3; males = 3; aged 14 years) attempted to respond to the ARCS. Both test protocol and process data were gathered. Data were thematically analysed. Responses were adequate in 83% of the instances. Process factors that appeared to impact response rate and quality included language of administration, seating arrangement, and option to use drawing for the responses.