Communicative adjustments.

<p>Time spent on Target and Non-target locations (during event 2 in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0072667#pone-0072667-g001" target="_blank">Figure 1B</a>; mean ± SEM; average time per trial) by the participants as a function of presumed Addressee (Toddler, Child).</p

Effect of daycare attendance on communicative adjustments.

<p>Individual communicative adjustments of 5-year-old participants plotted against days spent at daycare before starting school (mean of ages 0 to 4). Communicative adjustment was indexed by the relative difference of time spent on Target locations (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0072667#pone-0072667-g002" target="_blank">Figure 2</a>) between presumed toddler and child Addressees.</p

Task setup.

<p>(A) The Communicator, a 5-year-old participant, sat next to an Experimenter who provided the task instructions and the trial-specific location of the acorn but played no part in the communicative game. The Addressee, a confederate who performed the role of a toddler and a child (see panel C), while remaining blind to which one of the two roles he was performing in any given trial, sat outside the experimental room facing another monitor. (B) Each single trial encompassed four successive events. (1) the Experimenter showed to the Communicator only the location of the acorn (see panel A), and the Communicator had unlimited time to plan the movements; (2) the Communicator moved the bird icon on the game board by touching a touch-screen with a finger (the movements of the bird were visible to both Communicator and Addressee); (3) the Addressee moved the squirrel icon on the game board with a digital mouse (the movements of the squirrel were visible to both Communicator and Addressee); (4) both players received common feedback on the communicative success of the trial. Note that the bird, unlike the squirrel which could move freely, could only move to the center of each of the nine grid squares, and only through vertical or horizontal displacements. This feature of the task made it difficult for the Communicator and the Addressee to discriminate the location of multiple potential targets within a square (the white circles) on the basis of the location of the bird alone. (C) A digital photograph of the current presumed addressee was presented to the Communicator in full screen before the onset of each block of 5 trials, and in the top right corner during each block.</p

Example stimuli used in the experiment.

<p>For each object pair an action sequence was constructed, consisting of 3 action snapshots (left column, middle column and right column). The correctness of the object grasped and the grip applied to the object were independently manipulated, resulting in action sequences representing an actor (1) grasping the correct object with a correct grip (upper row), (2) grasping the correct object with an incorrect grip (2^nd row), (3) grasping the incorrect object with a correct grip (3^rd row) or (4) grasping the incorrect object with an incorrect grip (bottom row).</p

Behavioral results.

<p>Error rates in response to object questions (left graph) or to grip questions (right graph). Bars on the left represent responses to action sequences representing grasping of the correct object, bars on the right represent responses to action sequences representing grasping of the incorrect object. Light bars represent responses to action sequences representing a correct grip, dark bars represent responses to action sequences representing an incorrect grip.</p

ERPs relative to the onset of the 2^nd picture.

<p>ERPs relative to the onset of the 2^nd picture for a selection of central electrodes. Topographical plots represent the difference between Incorrect and Correct Objects (upper panel) and the difference between Incorrect and Correct Grips (middle panel. The lower panel reflects the t-values for the comparison between the Object Effect (Incorrect – Correct Object) and the Grip Effect (Incorrect – Correct Grip). The critical t-values are marked in red and a positive t-value reflects a stronger effect of Object than of Grip and a negative t-value reflects a stronger effect of Grip than of Object.</p

Object pairs used in the EEG experiment.

<p>The left column represents tools that had a high probability of being grasped first. The right column represents target objects towards which the tools could be moved. Object pairs marked with an asterisk were used as practice trials and were not included in the main EEG experiment.</p

Schematic overview of a trial sequence.

<p>Each trial started with a fixation cross, after which the action sequence was presented, consisting of 3 action snapshots. Following the action sequence either an object question (left side) or a grip question (right side) could be presented. Mapping of the response buttons (left/right) varied between trials and was presented below the question. After the subject responded a blank screen was presented.</p

Participants’ individual action-congruency scores (left) and movement-congruency scores (right) as a function of their self-reported Autism spectrum quotient scores (AQ; top) and empathic concern scores (IRI; bottom); r values denote spearman’s rho correlation coefficients.

<p>Significant correlations, as indicated by the * were found for action-congruency scores, but not for movement-congruency scores, (<i>p</i> < .05).</p

Participants’ mean response times in the action (conceptual)-control and movement (physical)-control conditions as a function of action (conceptual)-congruency and movement (physical)-congruency.

<p>Error bars represent standard errors of the mean (SEM). The asterisks indicate significant differences between conditions, * = <i>p</i> < .05, ** = <i>p</i> < .005.</p