Pavlovian theory of dreaming

Pavlovian theory provides a conceptual scheme for the examination of recent empirical data on dreaming. Consistencies are examined between these data and Pavlovian theory of the general properties of the nervous system. An equation is made between Pavlov’s excitation-inhibition continuum, the REM-NREM cycle, and the basic rest-activity cycle. Speculations, based on this equation, are made about the inter-relation between waking and sleeping behaviors. Testable hypotheses are suggested throughout the paper.     

Preference,resistance to change,and the cumulative decision model

According to behavioral momentum theory (Nevin & Grace, 2000a), preference in concurrent chains and resistance to change in multiple schedules are independent measures of a common construct representing reinforcement history. Here I review the original studies on preference and resistance to change in which reinforcement variables were manipulated parametrically, conducted by Nevin, Grace and colleagues between 1997 and 2002, as well as more recent research. The cumulative decision model proposed by Grace and colleagues for concurrent chains is shown to provide a good account of both preference and resistance to change, and is able to predict the increased sensitivity to reinforcer rate and magnitude observed with constant‐duration components. Residuals from fits of the cumulative decision model to preference and resistance to change data were positively correlated, supporting the prediction of behavioral momentum theory. Although some questions remain, the learning process assumed by the cumulative decision model, in which outcomes are compared against a criterion that represents the average outcome value in the current context, may provide a plausible model for the acquisition of differential resistance to change.     

Rat choice in rapidly changing concurrent schedules

In two experiments, experimentally naïve rats were trained in concurrent variable‐interval schedules in which the reinforcer ratios changed daily according to a pseudorandom binary sequence. In Experiment 1, relative response rates showed clear sensitivity to current‐session reinforcer ratios, but not to previous sessions' reinforcer ratios. Within sessions, sensitivity to the current session's reinforcement rates increased steadily, and by session end, response ratios approached matching to the current‐session reinforcer ratios. Across sessions, sensitivity to the current session's reinforcer ratio decreased with continued exposure to the pseudorandom binary sequence, contrary to expectations based on previous studies demonstrating learning sets. Using a second group of naïve rats, Experiment 2 replicated the main results from Experiment 1 and showed that although there were increases over sessions in both changeover rate and response rate during the changeover delay, neither could explain the accompanying reductions in sensitivity. We consider the role of reinforcement history, showing that our results can be simulated using two separate representations, one local and one nonlocal, but a more complex approach will be needed to bring together these results and other history effects such as learning sets and spontaneous recovery.     

A simultaneous test of the relationship between identified psychosocial risk factors and recurrent events in coronary artery disease patients

Psychosocial factors are increasingly recognized as risk indicators for coronary artery disease (CAD) prognosis and they are likely interrelated. The objective of this study is to simultaneously test the relationship between key psychosocial constructs as independent factor scores and recurrent events in CAD patients. There were 1268 CAD outpatients of 97 cardiologists surveyed at two points. Recurrent events or hospitalization in the intervening nine months were reported. Factor analysis of items from the Hospital Anxiety and Depression Scale, Perceived Stress Scale, the ENRICHD Social Support Inventory, and Hostile Attitudes Scale was performed to generate orthogonal factor scores. With adjustment for prognostic variables, logistic regression analysis was performed to examine the relationship between these factor scores and recurrent events. Factor analysis resulted in a six-factor solution: hostility, stress, anxiety, depressive symptoms, support, and resilience. Logistic regression revealed that functional status and anxiety, with a trend for depressive symptoms, were related to experiencing a recurrent event. In this simultaneous test of psychosocial constructs hypothesized to relate to cardiac prognosis, anxiety may be a particularly hazardous psychosocial factor. While replication is warranted, efforts to investigate the potential benefits of screening and to investigate treatments are needed.     

Pigeons' categorization may be exclusively nonanalytic

Recent theoretical and empirical developments in human category learning have differentiated an analytic, rule-based system of category learning from a nonanalytic system that integrates information across stimulus dimensions. In the present study, the researchers applied this theoretical distinction to pigeons' category learning. Pigeons learned to categorize stimuli varying in the tilt and width of their internal striping. The matched category problems had either a unidimensional (rule-based) or multidimensional (information-integration) solution. Whereas humans and nonhuman primates strongly dimensionalize these stimuli and learn rule-based tasks far more quickly than information-integration tasks, pigeons learned the two tasks equally quickly to the same accuracy level. Pigeons may represent a cognitive system in which the commitment to dimensional analysis and category rules was not strongly made. Their performance could suggest the character of the ancestral vertebrate categorization system from which that of primates emerged.