Authors:

CUSACK, R., & CARLYON, R.P

Reference:

Year of publication:

2002

CBU number:

5404

Abstract:

Visual search experiments have demonstrated that selecting a target from distractors is usually easier when the target excites a neural population of feature detectors that the distractors do not. In audition, many authors have proposed a stage of feature extraction before recognition, a position supported by neurophysiological evidence, and we might therefore expect to see search asymmetries. We describe six experiments investigating this hypothesis. Strong perceptual asymmetries were identified, with frequency modulated targets easier to detect amongst pure tone distractors than vice-versa. This asymmetry occurred both when the sounds were entirely sequential and the modulation close to threshold, and when the modulation was highly suprathreshold and many possibly overlapping sounds were presented. An asymmetry was also found for duration, with longer sounds easier to select from short distractors than the reverse. We demonstrate that the asymmetries are not a result of peripheral limitations. In contrast, no asymmetries were observed between high- and low- frequency tones, or between short three-tone sequences differing only in their temporal structure. We discuss the potential of this paradigm for identifying further feature extractors and elucidating the neural coding strategies in the auditory system.Supported by: Medical Research Council, UK