Sensitivity.

<p>Sensitivity (<i>d</i>') for the communicative (black line) and individual (gray line) condition in the three timing sets. Error bars represents standard errors. The dashed line (<i>d</i>' = .95) represents the 75% correct responses level selected during the training session, in which agent B was presented alone.</p

Example of a communicative signal trial.

<p>Agent A points to an object to be picked up; agent B bends down and picks it up. B was presented using limited-lifetime technique (6 signal dots) and masked with temporally scrambled noise dots. The noise level displayed is the minimum allowed in the experiment (5 noise dots). To provide a static depiction of the animated sequence, dots extracted from 3 different frames are superimposed and simultaneously represented; the silhouette depicting the human form was not visible in the stimulus display.</p

Sensitivity (d') in the two experimental conditions.

<p>Error bars represents 95% confidence intervals.</p

Scatter plot showing the correlation between communicative action identification and d'.

<p>Identification scores are plotted on the ordinate, and represent the percentage of participants who correctly identified A's communicative actions (normative data <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0014594#pone.0014594-Manera1" target="_blank">[12]</a>). The difference between communicative condition and individual condition is plotted on the abscissa (<i>d'</i>). The black line represents the linear regression line fitted to the data.</p

SDT parameters for the two experimental conditions.

<p>Error bars are 95% confidence intervals.</p

Experimental design.

<p>Example of communicative point-light action. Agent A asks B to walk away. Agent B starts walking in the required direction. Please note that n the original stimulus display, the points were white on a black background, and the silhouette depicting the human form was not visible. Task A. Participants were asked to decide whether the two agents were communicating or acting independently of each other. Task B. Participants were asked to select the correct action description among five response alternatives (correct response: 1).</p

Illustration of a bistable point-light walker.

<p>Illustration of a single frame of the bistable point-light walker (without perspective cues), and the two veridical interpretations with the point-lights superimposed. Whilst both veridical interpretations are equally plausible, observers usually prefer the FV interpretation. Thus, the objectively bistable point-light walker does not correspond to the subjectively bistable one. To obtain <i>subjectively</i> bistable stimuli, we performed a preliminary adjustment task in which perspective cues carrying the information concerning the veridical orientation of the point-light figure were gradually manipulated. On each trial, participants were asked to indicate whether the visually presented stimulus was perceived as FV or FAV. Individual perspective levels were determined by fitting a cumulative Gaussian function to the proportion of FV responses in the different perspective conditions, and selecting the perspective manipulation corresponding to the 30%, 50%, and 70% FV thresholds.</p

Example of a communicative signal trial.

<p>Agent A points to an object to be picked up; agent B bends down and picks it up. B was presented using limited-lifetime technique (6 signal dots) and masked with temporally scrambled noise dots. The noise level displayed is the minimum allowed in the experiment (5 noise dots). To provide a static depiction of the animated sequence, dots extracted from 3 different frames are superimposed and simultaneously represented; the silhouette depicting the human form was not visible in the stimulus display.</p

Correlations between Communicative intention recognition task (task A and task B) and Mental Rotation task (panels a and b) and Face task (panels c and d) for schizophrenic participants and healthy controls.

<p>Correlations between Communicative intention recognition task (task A and task B) and Mental Rotation task (panels a and b) and Face task (panels c and d) for schizophrenic participants and healthy controls.</p

SDT parameters for the three experimental conditions.

<p>Error bars are 95% confidence intervals.</p