Be�ta Tomoriov�1, Rudolf Andoga1, Michal Barto1, Norbert Kopčo1,2
1 Dept. of Cybernetics and Artificial Intelligence, Technical University of Ko�ice, Slovakia,
2 Dept. of Cognitive and Neural Systems, Boston University
beata.tomoriova@tuke.sk, rudolf.andoga@tuke.sk, michal.barto@gmail.com, kopco@bu.edu
Experiment was performed to examine the influence of auditory context on sound localization. The experiment followed up on a previous study of sound localization with a preceding distractor, which found that localization responses are biased away from the distractor location even on interleaved baseline trials on which targets are preceded by no distractor [Kopco et al., JASA, 121, 420-432, 2007].
Subjects� task was to localize a 2-ms noise burst presented from one of seven locations either from the left or right frontal hemifield. On some trials (the distractor trials) a distractor, identical to the target and originating directly ahead of the listener, preceded the target. The distractor-target temporal characteristics were explored by parametrically changing the percentage of non-distractor trials within a block (10%, 25%, or 50%) and the distrator-to-target onset asynchrony (SOA: 25, 100, or 400 ms). Performance was evaluated by comparing the responses on the non-distractor trials of the distractor blocks to baseline performance (blocks that presented only non-distractor trials).
Results showed that localization was biased away from the distractor, even when only 50% of the trails contained the distractor and even at the longest SOAs. The temporal parameters had only small effect: shifts at the shortest SOAs and at lower percentage of non-distrator trials were slightly larger. The results suggest that the contextual shifts in sound localization are relatively insensitive to manipulations in temporal characteristics of the stimuli.
[Supported by NIH #1R03TW007640 and VEGA #1/0445/09]