Skip to main content
Log in

Pupillary dilation response as an indicator of auditory discrimination in the barn owl

Journal of Comparative Physiology A Aims and scope Submit manuscript

Abstract

The pupil of an awake, untrained, head-restrained barn owl was found to dilate in response to sounds with a latency of about 25 ms. The magnitude of the dilation scaled with signal-to-noise ratio. The dilation response habituated when a sound was repeated, but recovered when stimulus frequency or location was changed. The magnitude of the recovered response was related to the degree to which habituating and novel stimuli differed and was therefore exploited to measure frequency and spatial discrimination. Frequency discrimination was examined by habituating the response to a reference tone at 3 kHz or 6 kHz and determining the minimum change in frequency required to induce recovery. We observed frequency discrimination of 125 Hz at 3 kHz and 250 Hz at 6 kHz – values comparable to those reported by others using an operant task. Spatial discrimination was assessed by habituating the response to a stimulus from one location and determining the minimum horizontal speaker separation required for recovery. This yielded the first measure of the minimum audible angle in the barn owl: 3° for broadband noise and 4.5° for narrowband noise. The acoustically evoked pupillary dilation is thus a promising indicator of auditory discrimination requiring neither training nor aversive stimuli.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Author information

Authors and Affiliations

Authors

Additional information

Accepted: 28 February 2000

Rights and permissions

Reprints and permissions

About this article

Cite this article

Bala, A., Takahashi, T. Pupillary dilation response as an indicator of auditory discrimination in the barn owl. J Comp Physiol A 186, 425–434 (2000). https://doi.org/10.1007/s003590050442

Download citation

  • Issue Date:

  • DOI: https://doi.org/10.1007/s003590050442

Navigation