Elephants know when their bodies are obstacles to success in a novel transfer task

Abstract

The capacity to recognise oneself as separate from other individuals and objects is difficult to investigate in non-human animals. The hallmark empirical assessment, the mirror self-recognition test, focuses on an animal's ability to recognise itself in a mirror and success has thus far been demonstrated in only a small number of species with a keen interest in their own visual reflection. Adapting a recent study done with children, we designed a new body-awareness paradigm for testing an animal's understanding of its place in its environment. In this task, Asian elephants (Elephas maximus) were required to step onto a mat and pick up a stick attached to it by rope, and then pass the stick forward to an experimenter. In order to do the latter, the elephants had to see their body as an obstacle to success and first remove their weight from the mat before attempting to transfer the stick. The elephants got off the mat in the test significantly more often than in controls, where getting off the mat was unnecessary. This task helps level the playing field for non-visual species tested on cognition tasks and may help better define the continuum on which body- and self-awareness lie.

Figure 1. Set-up of test trials.

Once standing on the mat, elephants were instructed to pick up the stick and give it to the experimenter. Drawing by E. Gilchrist.

Figure 2. Percentage of trials subjects fully removed their weight from the mat in each condition.

Boxplots represent 25th and 75th percentiles, centre line indicates the median, whiskers represent non-outlier range and dots are outliers. Significance levels: ** < 0.005, * < 0.01, ns = non-significant.

Figure 3. Individual performance of each subject on the first test session.

The line represents statistical significance above chance level.

Figure 4. Mean number of trials [/12] subjects got off the mat in the first session of the test and foot discomfort conditions.

*** < 0.0001.

Figure 5. Set-up of the foot discomfort control.

Once on the mat, elephants were requested to pick up flip flops and pass them to the experimenter whilst a second experimenter tugged on the rope at regular intervals. Drawing by E. Gilchrist.