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Psychologists routinely attribute the characteristics of conditioned behavior to complicated cognitive processes. For example, many of the characteristics of behavior undergoing extinction have been attributed to retrieval from memory. The authors argue that these characteristics may result from the simpler process of habituation. In particular, conditioned(More)
Multiple chemical sensitivity (MCS) is an ill-defined disorder in humans attributed to exposure to volatile organic compounds. This study draws on apparent parallels between individuals with posttraumatic stress disorder (PTSD) and panic disorder and a subset of those reporting MCS, using a conditioned fear task in rats. Male and female Sprague-Dawley rats(More)
Chemical intolerance is a phenomenon observed in multiple chemical sensitivity (MCS) syndrome, an ill-defined disorder in humans attributed to exposure to volatile organic compounds. Amplification of symptoms in individuals with MCS resembles the phenomenon of psychostimulant- and stress-induced sensitization in rodents. We have recently tested in rats the(More)
A trigonometrically fitted block Numerov type method (TBNM), is proposed for solving y′′ = f(x, y, y′) directly without reducing it to an equivalent first order system. This is achieved by constructing a continuous representation of the trigonometrically fitted Numerov method (CTNM) and using it to generate the well known trigonometrically fitted Numerov(More)
Rats pressed keys or levers for water reinforcers delivered by several multiple variable-interval schedules. The programmed rate of reinforcement varied from 15 to 240 reinforcers per hour in different conditions. Responding usually increased and then decreased within experimental sessions. As for food reinforcers, the within-session changes in both lever(More)
Five rats pressed levers for food delivered by a multiple variable interval 1-min variable interval 1-min schedule. In theunpredictable conditions, sessions were 20, 40, 60, 80, or 100 min long, determined randomly at the beginning of each session. In thepredictable conditions, each of these session durations was presented for 15 consecutive sessions. Rate(More)
Four rats and four pigeons responded for food delivered by variable interval schedules that provided programmed rates of reinforcement ranging from 15 to 480 reinforcers per hour. Rate of responding increased, decreased, or increased and then decreased within sessions. The within-session pattern of responding changed with changes in the programmed rate of(More)
Behavioral contrast can be defined as an inverse relation between rate of responding in one component of a multiple schedule and conditions of reinforcement in the other components. The present study was an attempt to produce contrast with changes in duration of reinforcement. Pigeons pecked a key for mixed grain delivered by a multiple variable-interval(More)
Three pigeons pecked keys and 5 rats pressed levers for food delivered on variable-interval schedules. During baseline conditions, subjects responded on a variable-interval 40-s schedule throughout the session. During experimental conditions, the programmed rate of reinforcement changed every 10 min in the 50-min sessions. When rats served as subjects,(More)