Repulsive serial effects in visual numerosity judgments

<p>Data pertaining to the study entitled "Repulsive serial effects in visual numerosity judgments". A description of the data format is contained in the Datadescription.txt file.</p

Results of Experiment 3: Modulation of radial and tangential errors along the horizontal diameter.

<p>Average Constant Errors (CE) made when reproducing points locations along the horizontal diameter (7 points by 2 radii, see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0151488#pone.0151488.g002" target="_blank">Fig 2A</a>), expressed in pixels. The same conventions used in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0151488#pone.0151488.g003" target="_blank">Fig 3</a> are adopted here.</p

Experiment 2: Experimental design, expected and observed results.

<p><i>Panel A</i> illustrates the design used in Experiment 2, which is identical to that used in Experiment 1: 57 points belonging to the inner area of a square (side length: 16.3 degrees of visual angle) were presented. 56 points were distributed along 8 radii (from 0° to 315°) at 7 equally-spaced locations for each radius (labels 1 to 7). The remaining last point coincided with the center of the square. <i>Panel B</i>. The experimental procedure was the same as in Experiment 1. As in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0151488#pone.0151488.g001" target="_blank">Fig 1B</a>, expected results are illustrated by the curve <b>C</b> which represents the hypothetical modulation of estimation error between the center and the periphery. The black curve represents the empirical contour line of null error actually estimated by participants in Experiment 2.</p

Trial sequence.

<p>Observers viewed the stimuli through a black 680x1000 mm reduction screen with a circular hole (280 mm in diameter) cut out at its center and fixed at 6 cm in front of the computer monitor. Each trial began with a homogenous black screen lasting for 1200–1800 ms (meaning that the actual duration was randomly chosen in the interval). Then the circle outline (diameter: 16.3 degrees of visual angle) was presented (panel 1) and 300–500 ms later the small target disk was added to the display (panel 2). The whole stimulus (circle plus target) remained visible for 1500 ms. It was followed by a black screen for 500 ms (panel 3), and, then, by a masking screen for 1000 ms (panel 4). The screen went black again for 500 ms (panel 5), and then only the circle was displayed with a position jitter (with coordinates randomly chosen in an interval of ±3 degrees of visual angle independently on the X and Y axes). Afterwards, a crosshair cursor was displayed behind the reduction screen in a screen quadrant that did not contain the target. Participants were required to move the cursor inside the visible area in order to reproduce the previously seen target position: they clicked the mouse once they had achieved the exact match (panel 6). Stimuli are not drawn to scale.</p

Results of Experiment 2: Modulation of radial and tangential errors.

<p>Average Constant Errors (CE) made when reproducing points locations, expressed in pixels. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0151488#pone.0151488.g004" target="_blank">Fig 4</a> follows the same conventions adopted in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0151488#pone.0151488.g002" target="_blank">Fig 2</a>.</p

Results of Experiment 1: Modulation of radial and tangential errors.

<p>Average Constant Errors (CE) made when reproducing points locations (7 points by 8 radii, see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0151488#pone.0151488.g001" target="_blank">Fig 1A</a>), expressed in pixels. Black curves represent the radial component of the CE (i.e. the displacement along the direction of the corresponding radius). Positive values indicate displacement toward the periphery, negative toward the center. Black dotted lines and empty squares illustrate the expected null radial error at points placed on the circumference and at the center (respectively after 7 and before 1). Grey curves represent the tangential component of the CE (i.e. the lateral deviation from the radius direction, orthogonal to it). Positive values refer to clockwise deviations. Error bars represent the standard error of the mean.</p

Experiment 1: Relation between curvature and duration.

<p>The shapes below the x-axis reproduce the trajectories used as templates for movements (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0051191#pone-0051191-g001" target="_blank">Fig. 1B</a>). (A) Mean duration of actual and mental movements computed over 12 participants. (B) Variability over replications. The disks correspond to the mean SDs over subjects. The error bars represent the 95% Confidence Interval.</p

Preliminary experiment, velocity profile.

<p>Upward (dark grey) and downward (light grey) movement velocity profile of a typical subject, normalized on amplitude and duration (MD). On the bottom the Time to Peak Velocity values (TPV) of these movements are reported.</p

Experiment 3: Relation between curvature and duration in fixation condition.

<p>(A) Mean and 95% Confidence Interval of durations of actual and mental movements (N = 8).</p

Differences in movement execution after the observation of biological (red circles) and non-biological (violating biological laws, green circles) motions: linear relationship between participant (<i>y</i>-axis) and stimuli velocities (<i>x</i>-axis) for upward movements in implicit task.

<p>The circles represent participants' movement velocities after observing the moving stimuli and the vertical error bars refer to the standard deviations values. The dashed lines are the results of the linear regression model applied on the data.</p