Horner,

Horner and Staddon (1987) argued that a class of reward-following processes defined by a property they termed ratio invariance is a better model for the probabilistic choice performance of

Two accounts of how density of reinforcement affects steady-state performance on probabilistic schedules were compared: the real-time linear operator (RTLO) model and a temporal control model (in which response strength is determined by reinforcement probability as a function of postreinforcement time). In Experiment 1, the probability of reinforcement repeatedly cycled between extinction and a random-ratio 10 schedule. Response-rate gain and phase did not change with period of the cycle as predicted by the RTLO model, nor did either model predict the differences in response rate following reinforcement at different points in the cycle. In Experiment 2, the probability of reinforcement was elevated immediately following a reinforcement but fell after a few seconds. Previous reinforcements had no effect upon responding. An extension of the temporal control model, the cumulative impulse model, allowed for the summing of response strength over successive reinforcements and was consistent with the data of both experiments.Many accounts of foraging and behavior on reinforcement schedules (Charnov, 1976;Herrnstein, 1961Herrnstein, , 1990Herrnstein & Vaughan, 1980) assume that behavior is driven by the animal's estimate of prey density or foodreinforcement rate. How do animals form this estimate from the stream of discrete feeding episodes? Two very different approaches have been taken to this problem. The most popular view in the literature on foraging is that behavior is guided by some form of moving average of local reinforcement rate, referred throughout here as the real-time linear operator (RTLO) model, described by Lea and Dow (

No abstract

The Colorado College Two experiments replicated Bruner and Postman (1949), on which Kuhn (1962, 1970) relied in his argument that humans resist experience that is incongruous with their expectations-an argument essential to Kuhn's thesis of scientific revolutions. The first experiment measured reaction times for identifying playing card stimuli in three conditions: (a) where all the stimuli were standard playing cards, (b) where stimuli had color reversed (trick), or (c) which included both regular and trick card stimuli (mixed set). Participants were equally adept at identifying regular and trick stimuli in homogenous sets but took longer to identify the same stimuli in a mixed set. The second experiment, a conceptual replication of Bruner and Postman's original experiment, obtained recognition thresholds for regular and trick stimuli while measuring participants' frustration. Participants responded similarly to procedural difficulties for both trick and regular stimuli. An analysis of participants' responses shows that participants used systematic trial-and-error strategy to identify any ambiguous stimulus. These findings are inconsistent with an interpretation of resistance to incongruities.