An infrared system for the detection of a pigeon''s pecks at alphanumeric characters on a TV screen: the dependency of letter detection on the predictability of one letter by another.

Three pigeons pecked at letters of the alphabet and at the symbol "?" displayed on a computer-driven cathode ray screen. A 4 by 4 matrix of infrared emitting and detecting diodes and associated circuitry identified the location of a pigeon''s responses to the screen. Responses at the target letter T were probabilistically reinforced with food whenever T appeared in a string of three letters in the middle of the screen. Responses at the symbol "?" appearing below this string were probabilistically reinforced whenever T did not appear. The letter F anywhere in the three-character string either strongly predicted the occurrence of the target letter T, in two conditions, or predicted its nonoccurrence, in a third. This manipulation of the frequency with which the familiar letter F predicted T was shown to change the function relating probability of a correct peck at the symbol "?" to the number of Fs in the string. This effect may be interpreted as an instance of the phenomenon where an organism''s acquired knowledge changes what it sees.     

Color discrimination on Mangaia

Bornstein’s hypothesis that there is a loss of color discrimination in tropical areas was not supported in earlier research in the Cook Islands. Using a more sensitive color vision test (the Farnsworth-Munsell 100-Hue Test), a loss of color discrimination in the red-purple and blue-green regions of the spectrum was found. The lack of sex differences in this color discrimination loss supports a physiological rather than a genetic explanation of the observed decrement.     

Context effects in episodic studies of verbal and facial memory: A review

Memory research has in the last fifteen years been marked by a considerable interest in context effects. This review begins by examining experimental manipulations of verbal and environmental context in verbal memory. This is followed by a more extensive review of episodic studies of face recognition that have examined the effects of varying the background in which a face is portrayed, the room of testing, and the presence of guided instructions. The relevance of these findings to eyewitness memory is also considered. Discrepancies in the literature are pinpointed with theoretical discussion centering around encoding specificity theory (Tulving & Thomson, 1973) and Baddeley and Woodhead’s (1982) distinction between “independent” (extrinsic) and “interactive” (intrinsic) context effects. The review ends with an evaluation of some recent models of memory and face recognition in an attempt to provide a framework within which to interpret the context effects in the literature.     

Psychosocial risk factors, natural immunity, and cancer progression: Implications for intervention

One of the more important and emerging fields in which psychologists collaborate with other disciplines is psychoimmunology. Centuries of clinical anecdote and decades of psychosomatic hypotheses have gained credibility in the eyes of the medical establishment—and many patients—by the systematic investigation of mechanisms potentially explaining how events intrapsychic and interpersonal could affect physical disease processes. The central nervous system is connected with the immune system by both neuronal and endocrinological pathways. The immune system has been found to mediate the organism’s response to aberrations of its own normal functions, as well as to invading organisms from without. AIDS, arthritis, asthma, lupus, and herpes are some of the illnesses in which research is demonstrating important relationships among psychosocial and immunological factors and disease course. In this article, we first discuss the immunological apparatus in order to provide a base for subsequent discussions of the effects of stress on immune function. Then we discuss malignant diseases and current evidence that disease course is related to both psychosocial stressors and immune function. We next discuss a model of these interactions, and finally we talk about interventions incorporating psychosocial factors aimed at influencing immune status and, thus, disease course.     

The interaction of stimulus and reinforcer control in complex temporal discrimination.

Six pigeons were trained in a discrete-trials signal-detection procedure to discriminate between a fixed-duration stimulus (5 s or 20 s) and a set of variable durations ranging from 2.5 s to 57.5 s in steps of 5 s. For each fixed-duration stimulus, the ratio of reinforcer frequencies contingent upon reporting the fixed versus the variable stimulus was systematically manipulated. Detection performance was well controlled by both the stimulus value and the reinforcer ratio. Both the discriminability between the fixed duration and the set of variable durations, and the discriminability between the fixed duration and each of the variable durations, were independent of the reinforcer-frequency ratio when discriminability was measured as log d. The sensitivity of response bias to reinforcement-ratio changes was independent of the value of the fixed duration, but was not independent of the discriminability of the variable durations from the fixed durations. Under current models, discriminability measures in complex temporal discrimination may be independent of biasing manipulations, but bias measures are not independent of stimulus values.     

Choice between reliable and unreliable outcomes: mixed percentage-reinforcement in concurrent chains.

Pigeons' choices between alternatives that provided different percentages of reinforcement in mixed schedules were studied using the concurrent-chains procedure. In Experiment 1, the alternatives were terminal-link schedules that were equal in delay and magnitude of reinforcement, but that provided different percentages of reinforcement, with one schedule providing, reinforcement twice as reliably as the other. All pigeons preferred the more reliable schedule, and their level of preference was not systematically affected by variation in the absolute percentage values, or in the magnitude of reinforcement. In Experiment 2, preference for a schedule providing 100% reinforcement over one providing 33% reinforcement increased systematically with increases in the duration of the terminal links. In contrast, preference decreased systematically with increases in the duration of the initial links. Experiment 3 examined choice with equal percentages of reinforcement but unequal delays to reinforcement. Preference for the shorter delay to reinforcement was not systematically affected by variation in the absolute percentage of reinforcement. The overall pattern of results supported predictions based on an extension of the delay-reduction hypothesis to choice procedures involving mixed schedules of percentage reinforcement.     

Effects of delayed conditioned reinforcement in chain schedules.

The contingency between responding and stimulus change on a chain variable-interval 33-s, variable-interval 33-s, variable-interval 33-s schedule was weakened by interposing 3-s delays between either the first and second or the second and third links. No stimulus change signaled the delay interval and responses could occur during it, so the obtained delays were often shorter than the scheduled delay. When the delay occurred after the initial link, initial-link response rates decreased by an average of 77% with no systematic change in response rates in the second or third links. Response rates in the second link decreased an average of 59% when the delay followed that link, again with little effect on response rates in the first or third links. Because the effect of delaying stimulus change was comparable to the effect of delaying primary reinforcement in a simple variable-interval schedule, and the effect of the unsignaled delay was specific to the link in which the delay occurred, the results provide strong evidence for the concept of conditioned reinforcement.     

信息整合模型与中国人印象形成的特点

24名大学生各自独立地完成了两组由3×3因子设计的材料(人格特质形容词)构成的印象形成的任务。结果表明,信息整合理论的实验设计思想可以在中国文化的背景下应用。中国被试印象形成时的信息整合模型与西方学者的结果比较一致,但同时又体现出其独特的特点。文中对此做了讨论。     

汉字词笔划数对短时记忆容量的影响

短时记忆容量的测量有两种主要观点,即组块说和复诵回路说。本报告通过三项实验表明对汉字词短时记忆容量的测量应考虑字词的笔划复杂性。实验一使用频率相同的少笔划和多笔划汉字相比较,笔划少的字比笔划多的字记忆广度大;实验二用笔划数相近但音节长度不同的日本汉字相比较,发现音节长短对容量影响无显著差别;第三项实验是语音掩蔽对汉字词视听短时记忆的影响。结果表明视、听容量都下降,但视觉仍比听觉好。再一次指出汉字词短时记忆容量的测量应考虑其视觉特点。最后对汉字词笔划复杂性影响短时记忆容量的可能原因进行了讨论。