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.     

Constraints on access in a problem solving context

The effects of previously acquired information on a later problem solving task were explored. Prior research has shown that the acquisition of potentially relevant information is not effective for cuing solutions in a later problem solving task unless subjects are informed of the connection. The present research extends these results and demonstrates that the problem solving failure is not due to subjects’ rejecting the potentially relevant information following retrieval. Rather, the apparent failure to appropriately use previous information is a result of uninformed subjects’ inability to spontaneously access such information. Furthermore, the observed access failure is not reversible by simply informing the subjects of the task connection prior to a second trial. Finally, the results indicate that problem solving failure on a later informed trial is a problem-specific phenomenon that does not generalize to new problems. The implications for contemporary episodic memory paradigms and the role of access in learning theory are discussed.     

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.     

Lexical projection and the interaction of syntax and semantics in parsing

A series of self-paced reading studies utilized an embedded anomaly technique to investigate long-distance dependencies with dative verbs. Previous research i our lab demonstrated that argument structure influences the gap-filling process. Experiment I extended that work by demonstrating that dative verbs pattern with other complex transitive verbs (i.e., a fronted filler that is implausible as the direct object will not be interpreted as the direct object until the absence of a noun phrase after the verb forces the postulation of a direct object gap. This pattern contrasts with that of transitive verbs that subcategorize for a single internal argument position, where fronted fillers are obligatorily interpreted as the direct object). Experiments 2 and 3 investigate the prediction that semantic analyses precede syntactic analyses in dative questions. It is argued that the lexical information about argument structure and thematic roles can guide semantic interpretation.This research was supported in part by NSF grant BNS-8617738 and NIH grant HD-22271.     

Lexical structure in parsing long-distance dependencies

We review a series of experiments investigating lexical influences in parsing sentences with long-distance dependencies. We report three primary results. First, gaps are posited and filled immediately following verbs that are typically used transitively, even when the filler is an implausible object of the verb. However, gaps are not posited after verbs that are typically used intransitively. Second, plausibility determines whether or not a filler is treated as the object of a verb when the verb is typically used with both a direct object and an infinitive complement. Finally, verb control information is used immediately in determining which noun phrase will be interpreted as the understood subject of an infinitive complement.     

Personality and alcohol dependence

In this study, groups of ‘alcoholic’ subjects were independently rated as to their degree of dependence by a technique previously validated. The two groups of moderately and severely dependent subjects were then given the 101-item EPQ. In keeping with other similar studies, the data suggested that high N, high P and low E in men were related to the Clinical Alcohol Personality. Further analysis of these and other data suggest that whilst raised N scores may be a spurious artefact which is a consequence of heavy alcohol consumption, the E and P findings may reflect stable predispositions. There were no sex differences, but there was a major group difference on P, with both severely dependent men and women scoring significantly higher than their less dependent counterparts.