Blocking of the response-reinforcer association: Additional evidence

Response rates maintained by free-operant schedules are sometimes reduced when a brief signal is interposed between the response and reinforcer. Early interpretations of this rate reduction were in terms of associative competition between the response and signal, analogous to blocking and overshadowing effects obtained in Pavlovian conditioning. But subsequent evidence has disputed this interpretation by showing that the signal enhances response rate in several circumstances. The present study attempted to define the conditions determining the different effects by investigating the role of signal location in the delay-of-reinforcement interval. When it occurred immediately after a response, response rate was enhanced. When it occurred at the end of the delay interval, immediately preceding the reinforcer, the signal decreased response rate. A similar decremental effect occurred when the signal occurred in the middle of the delay interval, contiguous with neither the response nor the reinforcer. Similar blocking effects occurred with a response acquisition procedure. The results demonstrate that blocking effects do indeed occur in instrumental conditioning but that the usual procedure of using signals immediately contingent on responding confounds such blocking effects with the competing effects of conditioned reinforcement/marking.     

Psychopathy,anxiety and malingering

Psychopathy is commonly measured as a low score on an Anxiety scale or as a high score on the MMPI Pd scale. The Pd scale, the Spielberger et al. Trait Anxiety scale and a short Achievement Motivation scale were administered to a random postal sample of 115 Australians. It was found that there was a high positive correlation between the Pd and Anxiety scales. This strongly supports Eysenck's theory that psychopaths are neurotic extraverts. A possible alternative explanation of the findings, however, is that the Pd scale may measure not psychopathy but malingering.     

Masking,aftereffect, and illusion in visual perception of curvature

Masking, aftereffect, and illusion paradigms were used to establish the spatial selectivity of curvature detectors in human vision. Arcs with the same chord orientation mask each other maximally when they are identical in radius and direction of curvature. There is gradual reduction in masking over an extensive spatial range as arcs diverge in curvature. The transition from convexity to concavity does not produce discontinuity in the masking function. The extent to which a straight line appears curved also depends on the curvature of arcs shown previously (aftereffect) or at the same time (illusion). It is suggested that these effects could occur through selective adaptation of detectors responsive to either global curvature or the orientation of local straight-line approximations within an arc. Evidence is reviewed in support of the latter interpretation.     

The free-operant partial reinforcement effect: A discrimination analysis

Twelve continuously reinforced rats were extinguished in a modified operant chamber, with an S^D for goal-approach after each bar-press. Three groups of twelve rats each trained under FR 10 were extinguished with the S^D for goal-approach after every 6, 10, or 14-bar-presses, respectively. Results showed: (1) number of bar-presses to extinction was a direct function of the bar-press to S^D ratio during extinction, (2) number of food or goal-approaches was independent of both training and extinction conditions, and (3) prior to the breakdown in discrimination a revised response-unit hypothesis, based on a discrimination analysis of the effect of intermittent reinforcement, accurately predicted the number of bar-presses for each FR group.     

Absence of binocular interaction between spatial and color attributes of visual stimuli

The hypothesis that induction of the McCollough effect (spatially selective color aftereffects) entails adaptation of monocularly driven detectors tuned to both spatial and color attributes of the visual stimulus was examined in four experiments. The McCollough effect could not be generated by displaying contour information to one eye and color information to the other eye during inspection, even in the absence of binocular rivalry. Nor was it possible to induce depth-specific color aftereffects following an inspection period during which random-dot stereograms were viewed, with crossed and uncrossed disparity seen in different colored light. Masking and aftereffect in the perception of stereoscopic depth were also nonselective to color; in both cases, perceptual distortion was controlled by stereospatial variables but not by the color relationship between the inspection and test stimuli. The results suggest that binocularly driven spatial detectors in human vision are insensitive to wavelength.     

The behavioral specificity of stimulation: A systems approach to procedural distinctions of classical and instrumental conditioning

This paper presents a new methodological approach to classical Pavlovian investigations. Using a yoked group for stimulus pairing trial pacing, behavioral occurrence frequencies, sequential behavior patterns, and behavioral change dynamics are analyzed for rats in both a non-discriminative and a general setting discrimination paradigm. Theoretical issues addressed by a variety of new dependent measures are discussed, and a special emphasis is placed on comparing instrumental and classical procedures as viewed from the behavioral perspective of the subject.     

Test-retest reliability and concurrent validity of the Morrow Assessment of Nausea and Emesis (MANE) for the assessment of cancer chemotherapy-related nausea and vomiting

The present study evaluated the concurrent validity of two assessment approaches for the measurement of cancer chemotherapy-related nausea and vomiting. The results indicated that the concurrent validity between the Morrow Assessment of Nausea and Emesis (MANE; Morrow, 1984b) and continuous self-monitoring and the reliability on the MANE were moderate. The heterotrait-monomethod and heterotrait-heteromethod matrices demonstrated moderate correlations among the frequency, severity, and duration of anticipatory nausea and vomiting as well as high correlations among the frequency, severity, and duration of posttreatment nausea and vomiting. Additionally, the heterotrait-monomethod matrices show a number of correlations above chance between anticipatory and posttreatment symptoms. The results are discussed in light of future research endeavors.This research was supported in part by Research Grant IN-150 from the American Cancer Society.     

Effects of electromyographic biofeedback on reaction time and movement time

The effects of electromyographic (EMG) biofeedback on reaction time (RT) and movement time (MT) were investigated utilizing 42 right-handed, male subjects from a university population. Subjects were randomly divided into three groups, a control group and two experimental groups. Both experimental groups were exposed to their EMG signals from their triceps brachii during the task, one experimental group received written information explaining the purpose of the EMG was to improve performance through biofeedback. Reaction times of the first block of 25 trials were significantly faster than those on the subsequent three blocks of trials for all groups. This provided evidence of learning. No other significant effects for reaction times were observed. Mean movement time for the EMG-only group was significantly slower than the means of either the Control group or EMG-Biofeedback group, with no difference between the latter two. The differences between experimental groups may have been related to alteration of strategy, anxiety, motivation.     

Rural America. Unique opportunities for health care delivery and health services research

A general deterioration is occurring in the quality of life of rural Americans, and it is affecting the quality of health and mental health service delivery. About 24% of the U.S. population lives in nonmetropolitan areas where the citizens are older, less well educated, have lower incomes, and are more homogeneous in terms of race and ethnicity. Medicare and private insurance discriminate against rural services in their reimbursement policies, and there is a shortage of health personnel in rural areas. However, there has been renewed congressional action to meet rural needs. Both the House and Senate have established rural caucuses, and an Office of Rural Health Policy has been established in the federal executive branch. Legislative successes were achieved between 1985 and 1988. Rural initiatives will provide psychology with unique opportunities in the next several years.