Well-developed spatial reversal learning abilities in harbor seals (Phoca vitulina)

Abstract

In this study, behavioral plasticity in harbor seals was investigated in spatial reversal learning tasks of varying complexities. We started with a classic spatial reversal learning experiment with no more than one reversal per day. The seals quickly learned the task and showed progressive improvement over reversals, one seal even reaching one-trial performance. In a second approach, one seal could complete multiple reversals occurring within a session. Again, a number of reversals were finished with only one error occurring at the beginning of a session as in experiment 1 which provides evidence that the seal adopted a strategy. In a final approach, reversals within a session were marked by an external cue. This way, an errorless performance of the experimental animal was achieved in up to three consecutive reversals. In conclusion, harbor seals master spatial, in contrast to visual, reversal learning experiments with ease. The underlying behavioral flexibility can help to optimize behaviors in fluctuating or changing environments.

Keywords: Behavioral flexibility; Cognition; Conditional reversal learning; Pinnipeds; Within session reversal.

Fig. 1

Experimental setup. At the beginning of every trial, the animal was stationing in a ring station (RS) attached to a large board (B). This board served to hide the experimenter during experiments. A spy hole (SH) within the board allowed the experimenter to oversee the actions taken place in front of the board. The two locations in space (Sl) to which the animal responded to in the course of the experiment were mounted on the opposite side of the basin to the left (Sll) and right side (Slr) from the point of view of the experimental animal

Fig. 2

Results of serial spatial reversal learning (experiment 1). Performance of a seal Moe and b seal Sam plotted per session. The horizontal solid line represents a performance of 80% correct choices which needed to be met or surpassed in one session to meet the learning criterion. The horizontal dotted line marks chance performance at 50% correct choices, and the two horizontal dashed lines the upper and lower significance level (p = 0.05). The grey vertical bars indicate the performance of the seals within a single reversal. c Error rate for seal Moe (filled circles) and seal Sam (filled squares) plotting the number of errors as a function of the reversals

Fig. 3

Results of spatial within-session reversal learning (experiment 2). Error rate over all within-session reversals; black solid line represents the linear regression model

Fig. 4

Results of conditional spatial reversal learning (experiment 3). a Frequency of correct shifts to the conditional cue in phase 1 of experiment 3; the 78 reversals conducted are grouped in blocks of ten, last block contains only nine reversals; black line shows regression line. b Frequency of correct shifts to the conditional cue in phase 2 of experiment 3; the 98 reversals are grouped in blocks of ten, last block contains only eight reversals; black line shows regression line. c Number of errors over the last 38 Rs; filled circles represent successful reversals with both criteria met: correct shift to the new S+ with the conditional cue and at least five correct trials in a row; open circles represent reversals during which one of the criteria was not met