Main test design.

<p>Main test design.</p

Handedness of pointing subjects.

<p>Handedness of pointing subjects.</p

The goal of ape pointing - Fig 2

<p>(<i>a</i>) On average, subjects spent more time pointing at the grapes per trial in the successful-look condition than in the failed-look condition (<i>p</i> = 0.016). (<i>b</i>) Subjects also spent more time pointing at the grapes in the first trial of the successful-look condition than in the first trial of the failed-look condition (<i>p</i> = 0.009). Results depicted are for points with eye contact. Box plots represent the interquartile range, minimum, and maximum values; depicted also are the means (crosses), medians (horizontal lines), and outliers (circles).</p

The goal of ape pointing - Fig 3

<p>(<i>a</i>) We found no significant difference in the average time that subjects spent away from the experimental window per trial between the sessions of the successful-look condition (<i>p</i> = 0.176). (<i>b</i>) On average, subjects spent more time away from the experimental window per trial during the second session of the failed-look condition compared to the first session (<i>p</i> = 0.009). Box plots represent the interquartile range, minimum, and maximum values; depicted also are the means (crosses), medians (horizontal lines), and outliers (circles).</p

Individual subject performance^*.

<p>Individual subject performance^{<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0195182#t004fn001" target="_blank">*</a>}.</p

The general experimental setup for all conditions.

<p>The general experimental setup for all conditions.</p

Main test participant information.

<p>Main test participant information.</p

We found no difference in the average time that subjects spent away from the experimental window per trial across the four sessions of the motivational condition.

<p>Box plots as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0195182#pone.0195182.g003" target="_blank">Fig 3</a>.</p

The average percentage of points with eye contact directed at the grapes per trial was high in all three conditions with no significant difference across conditions.

<p>Box plots represent the interquartile range, minimum, and maximum values; depicted also are the means (crosses), medians (horizontal lines), and outliers (circles).</p

Predicted mean fixation duration in ms for the four colours and sounds.

<p>Fig 2 represents the predicted mean fixation duration in the two groups for the four colours together with the four sounds. Values were calculated with a non-log-transformed dependent variable and represent the fixation duration in milliseconds. The four boxes represent the four types of sound, and the two groups are represented by the different shapes of the dots.</p