Evaluation of the ability of northern fur seals to perceive and visually discriminate images under the conditions of sleep loss

Abstract

This is the first study estimating the ability of sea mammals to perceive and analyze information under the conditions of an almost complete sleep deprivation.

Fig. 1.

Percent of errors and response latency in fur seals when discriminating the larger of two circles under the baseline conditions, 108-h sleep deprivation and during recovery. A and B—seal no. 1, B and C—seal no. 2. Different markers signify an average for the given pair of circles (20–17, 20–18, 20–19 and 20–19.5 cm) in consecutive tests. Duration of sleep deprivation is shown in hours. The dotted line on the diagrams of the top row marks the error value of random response (25%, more than 5 errors out of 20 trails, binomial test—p > 0.05). The response latencies are given for the tests in which the larger circle was located to the right side from the seal.

Fig. 2.

Mean percent of errors and response latency in two fur seals when discriminating the larger of two circles under the baseline conditions, 108-h sleep deprivation and during recovery. A, B and C—seal no. 1, D, E, and F—seal no. 2. The latency values are given separately for the tests when the larger circle was positioned to the right side (B and E) or left side (C and F) to the seals. The data are presented as mean M ± m standard error for each pair of circles for all tests under the baseline conditions, sleep deprivation and recovery. The dotted line marks the error value of random response.