Auditory detection and optimal response biases

Rats were trained to detect a signal consisting of an increment in the intensity of a random noise. The procedure was analogous to the yes-no method of human psychophysics, in that one response was defined as correct and reinforced with brain stimulation if the signal was presented, and another response was correct and reinforced if the noise alone was presented. Incorrect responses produced periods of time-out. Bias functions showing how the animals’ response probabilities varied as the signal intensity was reduced were obtained in two ways. In Experiment 1, the probability of presenting the signal was varied over four values between 0.4 and 0.6. In Experiment 2, the number of brain stimulations consequent upon a correct response in the presence of the signal was varied over four values between 3:1 and 1:2. Differences of 0.10 and 0.05 in the signal probability, and unit differences in the ratio of brain stimulations, resulted in distinctly different bias functions. Accuracy of detection increased with the signal intensity, and was independent of the animals’ response biases. When the signal probability was varied, the animals optimized the number of correct trials, and hence the number of brain stimulations obtained. When the ratio of brain stimulations was varied, the animals compromised between optimizing the number of correct trials and optimizing the number of brain stimulations obtained.     

Bias functions and operating characteristics of rats discriminating auditory stimuli

Rats were trained to discriminate between two bursts of random noise that differed in intensity. In a two-lever, discrete-trial procedure, correct responses were reinforced with brain stimulation, and incorrect responses produced timeout. Responding was studied as a function of the decibel difference between the stimuli, the probabilities of presenting the stimuli, the relative duration of timeout consequent upon the two types of incorrect responses, and the absolute duration of timeout consequent upon incorrect responses. The results showed that the distribution of responses between the two levers depended upon the stimulus probabilities, but were independent of either the absolute or relative durations of timeout. When the stimulus probabilities were varied, the response probabilities did not match the stimulus probabilities; when the relative durations of timeout were varied, the animals did not obtain the maximum rate of reinforcement per unit time. Instead, the animals distributed their responses so as to obtain the maximum number of reinforcements at each level of discrimination. In addition, the level of discrimination increased as a function of the decibel difference between the stimuli.     

Accessing the Eternal: Dreaming "The Dreaming" and Ceremonial Performance

Australian Aboriginal cosmology is centered on The Dreaming, which has an eternal nature. It has been referred to as “everywhen” to articulate its timelessness. Starting with the assumption that “waking” reality is only one type of experienced reality, we investigate the concept of timelessness as it pertains to the Aboriginal worldview. We begin by questioning whether in fact “Dreaming” is an appropriate translation of a complex Aboriginal concept, then discuss whether there is any relationship between dreaming and The Dreaming. We then discuss Aboriginal ceremonial performance, during which actors are said to become Dreaming Ancestors, using as a frame of reference the “flow” experience explicated by Mihaly Csikszentmihalyi together with Alfred Schutz's “mutual tuning‐in relationship.”     

An individual differences analysis of the self-teaching hypothesis

The self-teaching hypothesis suggests that children learn orthographic structure of words through the experience of phonologically recoding them. The current study is an individual differences analysis of the self-teaching hypothesis. A total of 40 children in Grades 2 and 3 (7-9 years of age) completed tests of phonological recoding, word identification, and orthographic knowledge. The relation of phonological recoding and word identification was significantly mediated by orthographic knowledge. Furthermore, two aspects of orthographic knowledge (perhaps word-specific and general orthographic knowledge) mediated different variance shared between phonological recoding and word identification. Results support an individual differences version of the self-teaching hypothesis and emphasize the importance of phonological recoding in the primary curriculum.