Richard Lester Solomon (1918–1995): Obituary.

Memorializes Richard Solomon, one of the major learning theorists of the 2nd half of the 20th century. Solomon was named the 1st James M. Skinner University Professor of Science in 1975, was elected to the National Academy of Sciences, and was awarded, among other honors, the Warren Medal for research by the Society of Experimental Psychologists, the American Psychological Association Distinguished Scientific Contribution Award, and the American Psychological Foundation's Award for Distinguished Teaching in Experimental Psychology. He conducted research on a broad array of topics such as word frequency and perceptual defense, children's estimation of the size of tokens, hoarding behaviors in rats, and personality ratings and sociometric patterns. His work made a major contribution to the exploration of Pavlovian conditioning. Other topics of research focused on in Solomon's laboratories included avoidance learning, learned helplessness, punishment, and the opponent-process theory of acquired motivation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Retraction of Ross and LoLordo findings concerning blocking in serial feature-positive discriminations.

Findings concerning the effectiveness of stimuli from various conditioning procedures in blocking conditioned excitation and occasion-setting functions of an added stimulus in a serial feature-positive discrimination training procedure (V. M. LoLordo and R. T. Ross; see record 1987-24106-001; Ross and LoLordo; see record 1987-14728-001) are retracted. Videotapes on which the published data were based were rescored by 2–5 people, most of whom were uninformed about group memberships of the Subjects. In no case did the rescoring confirm any of the original findings of blocking. Possible factors contributing to the discrepancies are discussed. The experiments should be repeated with feature stimuli that are less similar to each other and with several scorers, at least one of whom is unaware of the group assignment of the Subjects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Blocking during serial feature-positive discriminations: Associative versus occasion-setting functions.

Previous work indicates that during serial feature-positive discriminations (i.e., feature–trace interval/common element/food presentations and separate nonreinforced common element presentations) the feature (A) acquires an association with food (unconditioned stimulus [UCS]) and also a capacity to modulate the common element (X)–UCS relation, which has been termed occasion setting (OS). In the present 2 experiments with 32 male Sprague-Dawley rats, a blocking design, serial feature-positive discrimination procedures, and a behavioral observation technique were used to assess the relation between associative and OS functions acquired by stimuli. In Exp I, prior conditioning of associative and OS functions to A blocked acquisition of both stimulus functions by a novel stimulus (B) trained in compound with A. In Exp II, prior acquisition of an A–UCS association blocked acquisition of a B–UCS association but had no effect on acquisition of B's OS function. These outcomes are discussed (a) as indicating that associative and OS functions are independent and may be based on separate learning processes, (b) as extending the known conditions for acquisitions of OS, and (c) with regard to the theoretical implications of assuming independence of associative OS functions acquired by stimuli. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Associative and nonassociative theories of the UCS preexposure phenomenon: Implications for Pavlovian conditioning.

Excitatory Pavlovian conditioning of a discrete CS is attenuated by prior exposure to the UCS. The UCS preexposure phenomenon is observed in a variety of Pavlovian conditioning procedures as diverse as eyelid conditioning, the conditioned emotional response, and conditioned taste aversion learning. This article discusses the variables that affect the UCS preexposure phenomenon and uses this information in evaluating both associative and nonassociative accounts of the phenomenon. At least one associative account, based on context blocking, and at least one nonassociative account, based on central habituation of the emotional response to the UCS, remain viable. (71 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Drug exposure and the acquisition and retention of a conditioned taste aversion

Two experiments examined the effects of preexposure and postexposure to a drug on the acquisition and retention of a conditioned taste aversion induced by that drug. Experiment 1 demonstrated that although drug preexposure attenuated a subsequent conditioned aversion, repeated taste-drug pairings reversed the initial attenuation effect and resulted in nearly complete avoidance of consumption. Experiment 2, however, demonstrated that drug postexposure did not alter a previously established conditioned aversion, although the postexposure experiences were effective in attenuating a conditioned aversion to a second novel solution. It was suggested that conditioned aversions are mediated by ACTH and that preexposure to a drug results in tolerance to that drug, yielding a smaller ACTH response and thereby a weaker aversion.     

The Natural Sciences and Engineering Research Council: Policies, procedures, and criteria for awarding research grants in experimental psychology.

Describes the Grants Selection Committee of the Natural Sciences and Engineering Research Council, discusses research areas that are eligible for support, and reviews procedures for evaluating grant proposals and allocating funds. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Discrete signals for the unconditioned stimulus fail to overshadow contextual or temporal conditioning.

Conditioned freezing in Sprague-Dawley rats evoked by contextual and temporal cues that reliably preceded a shock unconditioned stimulus (UCS) was unaffected by the presence of a redundant conditioned stimulus (CS). No overshadowing of contextual and temporal conditioning was found after either 5 or 15 days of conditioning, regardless of whether the time of UCS presentation within sessions was fixed or alternated and despite efforts to minimize the influence of 2nd-order associations. These results suggest that contextual and temporal cues may acquire associative strength independently of discrete CSs under some conditions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A reevaluation of Rescorla's early dictums about Pavlovian conditioned inhibition.

R. A. Rescorla's (1969) recommendations concerning the logical and empirical operations for inferring Pavlovian conditioned inhibition were examined in light of modern comparison theories of Pavlovian conditioning and new data that question whether excitation and inhibition are opposite ends of a single continuum of associative strength. This reanalysis confirms Rescorla's dictum that the summation and retardation tests are a sufficient basis for inferring inhibition. No theoretical or empirical challenges since 1969 undermine the heuristic or explanatory power of that concept. However, passing both of the 2 operational tests may not be necessary: A conditioned stimulus/stimuli (CS) may be inhibitory, yet may not pass one or the other test. Recent changes in the conception of inhibition are also reviewed, and it is suggested that there may be other forms of associatively based inhibition that are not at all antagonistic to excitation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evaluation of the relation between Pavlovian occasion-setting and instrumental discriminative stimuli: A blocking analysis.

Retracted October 1990. (See record 1991-03475-001.) Conducted 2 experiments with 72 male Sprague-Dawley rats, using a blocking design (A+, then AB+) to assess the relation between Pavlovian occasion-setting and instrumental discriminative stimuli. Prior conditioning of both associative and occasion-setting functions of A in a serial feature-positive procedure blocked acquisition of an instrumental discriminative function by a novel stimulus (B) trained in compound with A. Neither prior conditioning of only an A/unconditioned stimulus/stimuli (UCS) association nor prior conditioning of Stimulus A using a Pavlovian simultaneous feature-positive procedure, which does not endow A with an occasion-setting function, blocked acquisition of an instrumental discriminative function by B. Prior acquisition of an instrumental discriminative function by A blocked acquisition of a Pavlovian occasion-setting function by a novel stimulus (B) trained in compound with A but did not block acquisition of an association between B and the UCS. (39 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Escape deficits following inescapable shock: The role of contextual odor.

Three experiments, with 192 male albino rats, examined the role of contextual odor in mediating deficits in escape performance produced by pretreatment with inescapable shock. Impaired leverpress performance (Exp I) and shuttle-escape performance (Exp II) were observed when the pretreatment and test chambers were odorized by previously shocked conspecifics. These deficits were eliminated in both experiments when the test chambers were thoroughly cleaned. Exp III determined whether the same odor must be present during pretreatment and testing, or whether mere exposure to a fear pheromone is sufficient to impair test performance. Shuttle escape was impaired only when the same odor was present in the pretreatment and test chambers. Results indicate that an odor common to the pretreatment and test chambers mediates impaired escape performance and suggests that other types of deficits observed following inescapable shock may also be mediated by such contextual cues. (36 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)