A comparison of latent inhibition and learned irrelevance pre-exposure effects in rabbit and human eyeblink conditioning

The learning of an association between a CS and a US can be retarded by unreinforced presentations of the CS alone (termed latent inhibition or LI) or by un-correlated presentations of the CS and US (termed learned irrelevance or LIRR). In rabbit eyeblink conditioning, there have been some recent failures to replicate LI. LIRR has been hypothesized as producing a stronger retardation effect than LI based on both empirical studies and computational models. In the work presented here, we examined the relative strength of LI and LIRR in eyeblink conditioning in rabbits and humans. In both species, a number of pre-exposure trials sufficient to produce LIRR failed to produce LI (Experiments 1 & 3). Doubling the number of CS pre-exposures did produce LI in rabbits (Experiment 2), but not in humans (Experiment 4). LI was demonstrated in humans only after manipulations including an increased inter-trial interval or ITI (Experiment 5). Overall, it appears that LIRR is a more easily producible pre-exposure retardation effect than LI for eyeblink conditioning in both rabbits and humans. Several theoretical mechanisms for LI including the conditioned attention theory, stimulus compression, novelty, and the switching theory are discussed as possible explanations for the differences between LIRR and LI. Overall, future work involving testing the neural substrates of pre-exposure effects may benefit from the use of LIRR rather than LI.     

Individual Orientation Toward Engagement in Social Action

The issue of how an activist identity develops is one of the core issues in social psychology and social movement research. Because of problems in the measurement of individuals' propensities to engage in social action, however, findings in this area are often equivocal, and cross–study comparisons and conclusions are difficult to draw. Hence, the aim of these studies was to develop a measure to assess individuals' propensities to engage in social action. This measure, the Activism Orientation Scale (AOS), demonstrates strong psychometric properties and allows assessment of activist propensity across a wide continuum of social action behaviors, ideological positions, and movement issues. Additionally, the broad applicability of the AOS allows for its use by researchers, activists, and policymakers.     

Acquired Equivalence Changes Stimulus Representations

Acquired equivalence is a paradigm in which generalization is increased between two superficially dissimilar stimuli (or antecedents) that have previously been associated with similar outcomes (or consequents). Several possible mechanisms have been proposed, including changes in stimulus representations, either in the form of added associations or a change of feature salience. A different way of conceptualizing acquired equivalence is in terms of strategic inference: Confronted with a choice on which it has no evidence, the organism may infer from its history of reinforcement what the best option is, and that inference is observed as acquired equivalence. To test this account, we combined an incremental learning task with an episodic memory test. Drawings of faces were made equivalent through acquired equivalence training, and then paired with words in a list learning paradigm. When participants were asked to recognize specific face-word pairings, they confused faces more often when they had been made equivalent. This suggests that prior acquired equivalence training does influence how memories are coded. We also tested whether this change in coding reflected acquisition of new associations, as suggested by the associative mediation account, or whether stimuli become more similar through a reweighting of stimulus features, as assumed by some categorization theories. Results supported the associative mediation view. We discuss similarities between this view and exemplar theories of categorization performance.     

Changing Structures in Midstream: Learning Along the Statistical Garden Path

Previous studies of auditory statistical learning have typically presented learners with sequential structural information that is uniformly distributed across the entire exposure corpus. Here we present learners with nonuniform distributions of structural information by altering the organization of trisyllabic nonsense words at midstream. When this structural change was unmarked by low-level acoustic cues, or even when cued by a pitch change, only the first of the two structures was learned. However, both structures were learned when there was an explicit cue to the midstream change or when exposure to the second structure was tripled in duration. These results demonstrate that successful extraction of the structure in an auditory statistical learning task reduces the ability to learn subsequent structures, unless the presence of two structures is marked explicitly or the exposure to the second is quite lengthy. The mechanisms by which learners detect and use changes in distributional information to maintain sensitivity to multiple structures are discussed from both behavioral and computational perspectives.     

Marital Status and Outcome in Patients with Coronary Heart Disease

The purpose of this study was to examine the relationship of marital status to health outcomes in 818 post-MI, coronary artery bypass surgery, and angioplasty patients (651 males, 157 females) from seven Northern California hospitals who completed 12 months of a nurse-managed, home-based multifactorial risk reduction program. Compared to married patients, nonmarried patients were significantly less likely to complete the program than married patients, more likely to smoke at baseline, and drank significantly less alcohol at baseline. At 12 months there were no significant differences between married and nonmarried groups on smoking cessation rates, HDL, LDL, triglycerides, or exercise treadmill test results. When patients were categorized as married, divorced, separated, widowed, or single, similar results were found for the analyses using two groups (married versus nonmarried), with the following exceptions. Separated patients were significantly less likely to quit smoking. In addition, separated patients showed significantly higher rates of starting (and continuing) to smoke during the time following their MI. Mortality was not significantly different between married and unmarried patients. Implications for intervention with separated patients and the importance of assessing both marital status and marital quality are discussed.     

The self in self-handicapping: Differential effects of public and private internal audiences

People self-handicap to satisfy both self-presentational and self-protective motives. The cognitive salience of a public or private audience, as well as the objective public or private situation, determines when each motive dominates. To show this, we manipulated the objective situation separately from the cognitive salience of public and private internal audiences. We hypothesized that in the objectively public situation, people would self-handicap more when focused on a public audience than when focused on a private audience; whereas in the objectively private situation, the reverse would occur. Two studies using different manipulations of audience salience supported the hypothesis. For self-presentational motives to foster self-handicapping, then, the person must not only be in public but must be cognitively focused on the public audience; and for self-protective motives to foster self-handicapping, the person must both be in private and cognitively focused on the private audience.     

Effects of cocaine exposure on infant development: A review

We review the effects of maternal cocaine use on the developing human fetus and infant in terms of methodological problems; the physiological action of cocaine on adults and on the developing fetus; the epidemiology of cocaine use; effects on fetal and infant mortality; growth of cocaine-exposed fetuses and infants; physical anomalies; evidence for and against infant withdrawal from cocaine; neurological effects; behavioral effects as shown by the NBAS; findings related to mother-infant interaction and emotional development; and parenting by cocaine-using mothers. Findings in most areas should be considered preliminary due to methodological problems. Published studies of long-term development are not yet available. In general, deleterious consequences of prenatal cocaine exposure are found for some portion of prenatally exposed infants. However, many findings of no difference are also available in methodologically well-controlled studies.     

Effects of reinforcer duration on responding in two-link chained interval schedules

Each of five pigeons was exposed to two or more durations of access to mixed grains on two-link, chained, interval schedules in which both links were identical fixed-interval or variable-interval schedules. Response rates were an increasing function of reinforcer duration for both initial and terminal links. For both types of interval schedules, initial-link response rates were more sensitive to reinforcer duration than were terminal-link response rates. The present results, together with prior ones, suggest that chaining and choice procedures are each sufficient for demonstrating substantial sensitivity of responding to changes in reinforcer duration.