Suboptimal choice in a percentage-reinforcement procedure: effects of signal condition and terminal-link length.

Pigeons' choice between reliable (100%) and unreliable (50%) reinforcement was studied using a concurrent-chains procedure. Initial links were fixed-ratio 1 schedules, and terminal links were equal fixed-time schedules. The duration of the terminal links was varied across conditions. The terminal link on the reliable side always ended in food; the terminal link on the unreliable side ended with food 50% of the time and otherwise with blackout. Different stimuli present during the 50% terminal links signaled food or blackout outcomes under signaled conditions but were uncorrelated with outcomes under unsignaled conditions. In signaled conditions, most pigeons displayed a nearly exclusive preference for the 100% alternative when terminal links were short (5 or 10 s), but with terminal links of 30 s or longer, preference for the 100% alternative was sharply reduced (often to below .5). In unsignaled conditions, most pigeons showed extreme preference for the 100% alternative with either short (5 s) or longer (30 s) terminal links. Thus, pigeons' choice between reliable and unreliable reinforcement is influenced by both the signal conditions on the unreliable alternative and the duration of the terminal-link delay. With a long delay and signaled outcomes, many pigeons display a suboptimal tendency to choose the unreliable side.     

Optimal choice

We present a classification and theoretical analysis of discrete-trial and free-operant choice procedures in which reinforcement is assigned to one alternative only, or independently to both, is either always available or conditionally available, and is either "held" or not from trial to trial. Momentary-maximizing and (globally) optimal choice sequences are defined in terms of initializing and marker events. Free-operant choice is analyzed in terms of a clock space whose axes are the times since the last A and B choices. The analysis shows that most molar matching data are derivable from momentary maximizing, and that the momentary-maximizing hypothesis has not been adequately tested in either discrete-trial or free-operant situations.     

A test of the reinforcing properties of stimuli correlated with nonreinforcement

The information hypothesis of conditioned reinforcement predicts that a stimulus that “reduces uncertainty” about the outcome of a trial will acquire reinforcing properties, even when the stimulus reliably predicts nonreinforcement. Four pigeons' key pecks produced one of two 5-sec stimuli with 0.50 probability according to a discriminated variable-interval schedule. One stimulus was followed by reinforcement; a second stimulus was followed by blackout. To the same extent, therefore, both stimuli reduced uncertainty about the possibility that food would arrive at the termination of the schedule interval. When a second key in the chamber was lighted, each peck on it could produce the stimulus preceding reinforcement, the stimulus preceding nonreinforcement, a novel stimulus, or no stimulus, across separate conditions. The stimulus preceding food maintained responding at substantial levels on the second, stimulus-producing, key. Such responding was not maintained by other stimuli. These data, replicated when the stimuli were reversed on the variable-interval schedule, do not support the prediction that uncertainty-reducing stimuli are necessarily conditioned reinforcers.     

Choice for conditioned reinforcers in the signaled absence of primary reinforcement

Pigeons responded in a multiple schedule in which concurrent schedules of brief-stimulus presentation alternated with a component in which food was available (concurrent-chains component). In the initial links of the concurrent-chains component subjects chose either of two stimuli each correlated with the terminal link of one chain. The terminal links involved either variable-interval 30-second or variable-interval 60-second schedules. In the brief-stimulus component subjects chose between 0.5-second presentations of the terminal-link stimuli from the concurrent-chains component. Responding was generally maintained in the brief-stimulus component in two subjects for more than 300 sessions, suggesting that brief stimuli were conditioned reinforcers. During the brief-stimulus component, in 17 of 21 cases for which a minimal number of responses occurred, choice proportions above 0.55 were obtained for the brief-stimulus presentations correlated with the higher rate of primary reinforcement in the concurrent-chains component. These results support the suggestion that choice in conventional concurrent-chains procedures is partially controlled by production of the terminal-link stimuli.     

Human observing: Maintained by stimuli correlated with reinforcement but not extinction

College students received points exchangeable for money (reinforcement) on a variable-time 60-second schedule that alternated randomly with an extinction component. Subjects were informed that responding would not influence either the rate or distribution of reinforcement. Instead, presses on either of two levers (“observing responses”) produced stimuli. In each of four experiments, stimuli positively correlated with reinforcement and/or stimuli uncorrelated with reinforcement were each chosen over stimuli correlated with extinction. These results are consistent with prior results from pigeons in supporting the conditioned-reinforcement hypothesis of observing and in not supporting the uncertainty-reduction hypothesis.     

道德直觉合乎道义却不客观

面对道德困境, 道德直觉倾向于促使人们做出道义论的判断。但是, 道德直觉易受情绪因素影响, 具有较强的主观性。道德直觉警惕有意图地使用个人力量造成的伤害, 却会接受由非个人力量或连带作用引发的伤害。“模块近视假说”认为, 大脑中存在一个预警系统, 能快速地对主动伤害的想法发出情绪警报。但该系统的审查机制是一种简单的“单通道”加工, 这种加工局限使连带作用造成的伤害避开了审查机制的监控。道德直觉的不客观提示, 面对现实生活中的道德争议, 不应该仅听凭直觉作为行动的依据。     

Graph Theory Approach to Detect Examinees Involved in Test Collusion

Test collusion (TC) is sharing of test materials or answers to test questions before or during the test (important special case of TC is item preknowledge). Because of potentially large advantages for examinees involved, TC poses a serious threat to the validity of score interpretations. The proposed approach applies graph theory methodology to response similarity analyses for identifying groups of examinees involved in TC without using any knowledge about parts of test that were affected by TC. The approach supports different response similarity indices (specific to a particular type of TC) and different types of groups (connected components, cliques, or near-cliques). A comparison with an up-to-date method using real and simulated data is presented. Possible extensions and practical recommendations are given.     

远离“城嚣”:自然对人的积极作用、理论及其应用

人类大部分进化时间都是在自然环境中发生的,自然在人的身心健康、认知功能等方面都有积极作用。3个主要的理论揭示了自然对人的积极作用:亲生命性假设认为亲近自然是人类的天性,并且会使人变得更健康和快乐;注意恢复理论认为人处于自然中使用的无意注意能对有意注意疲劳起到恢复作用;压力恢复理论认为接触自然能够激活人类的积极情绪,从而对压力有缓解作用。目前自然对人的积极作用已经在园艺疗法和自然环境疗法得到广泛应用。未来还可以从其他的心理学视角解释自然对人的积极作用,实证研究可以关注真实自然环境和虚拟自然环境的作用差别,还可以考察视觉以外的其他感觉通道接触自然的作用,并结合认知神经科学考察自然积极作用的神经机制。     

Inhibiting reactions to emotional versus non‐emotional response cues in schizophrenia: Insights from a motor‐process paradigm

Recent models of schizophrenia suggest deficient use of contextual response cues when confronted with countermanding emotional cues. It is important to clinically validate these models by testing patients diagnosed with schizophrenia on tasks with competing emotional and contextual response determinants. Control and schizophrenia groups completed a novel task that elicited motor responses consistent with, or in opposition to, pre‐potent emotional actions (i.e., approach vs. avoidance). An analogous non‐emotional task was also used to examine cue‐conflict impairment more generally. The groups demonstrated statistically equivalent performance decrements on incongruent versus congruent trials on both tasks. However, within the schizophrenia group, the incongruency effect was significantly greater in the emotional versus non‐emotional task. These data suggest that, while patients with schizophrenia were able to employ contextual response cues to override competing emotional responses, they were slower to resolve emotional versus non‐emotional response conflict. When patients were subdivided according to the presence or absence of disorganized symptoms, this effect was confined to patients with disorganized symptoms.     

Application of Variability of Practice Hypothesis in Alzheimer Patients

This study examined the effects of constant versus variable practice on learning a simple motor task in eight patients diagnosed with Alzheimer's Disease (AD). According to the variability of practice hypothesis, variations in practice of a motor skill result in superior learning as evidenced by better ability to transfer the skill. Eight AD patients were matched for Mini-Mental State Exam and baseline scores and then randomly assigned to a constant or variable practice group. Then, the participants were trained in hitting a tennis ball with a small racquet against a horizontal target (practice task) over 12 sessions. Finally, they were asked to aim at a vertical target (transfer task). All participants showed improvement on the practice task. On the transfer task, three of four participants in the variable practice group outperformed their matched counterparts, suggesting learning benefits of variable practice.