Human auditory information processing
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The purpose of this study is to investigate the flow of nonsymbolic auditory information in humans. To achieve this goal the observer adjusts the loudness of a Gaussian noise (GN) signal to match the perceived intensity of an electrodermal stimulus (EDS), a cross-modality matching task. The loudness of the GN and the voltage of the EDS mere maintained within the observer's (O's) sensory probabilistic zone. The sensory probabilistic zone is a range of stimulus intensity from somewhere above "no detection" to "100% detection". The independent variable is a binary condition in that it consisted of catch trials of the time and the remaining time of an EDS at a given intensity (previously determined at an intensity that elicited a response 50% of the time). Consequently, the O's adjustment of the GN reflected his decision-making processes, analysed by signal detection theory and cybernetics. Experiment one demonstrated that neither practice nor the experimenter influenced the O's performance. Also, there are no residual carry-over effects. The 0 has difficulty assigning relative value to the auditory signals and has little or no difficulty in combining, organizing or co-ordinating the auditory information. The second experiment demonstrated that the O's difficulty in assigning relative value to the signals is due to a short memory retention of the nonsymbolic auditory signals (half-life of less than a second). However, verbal confidence ratings (VCRs) add persistency to the auditory memory (echoic memory), its half-life is extended to about 3.1 seconds. The VCR has a half-life of about four seconds. Experiment three demonstrated that nonsymbolic auditory information processing is not affected by interfering signals. From a cybernetic model of the results it is concluded that nonsymbolic auditory information is processed by a filtered, single channel, series processor. Persistency is added to the system's memory component by an interaction between the auditory (echoic) memory and the conceptual symbolic system (VCR).
Thesis, PhD Doctor of Philosophy
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