Motion along the mental number line reveals shared representations for numerosity and space

<p>Single subject data from six experiments in "Motion along the mental number line reveals shared representations for numerosity and space" by Caspar M. Schwiedrzik, Benjamin Bernstein, and Lucia Melloni. </p

Reaction times.

<p>Subjects were faster when they perceived a face then when they did not, both in the upright and in the inverted condition (mean difference 29.8 ms, <i>T</i>(17) = 3.86, <i>p</i> = 0.001). They also showed a typical face inversion effect, taking longer to perceive inverted than upright Mooney faces (mean difference 38.9 ms, <i>T</i>(17) = 7.54, <i>p</i><0.001). No reaction time differences between perceived and non-perceived scrambled images were observed (mean difference 2.1 ms, <i>T</i>(17) = 0.11, <i>p</i> = 0.906). Error bars reflect the standard error of the mean, corrected for between-subject variability [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0200106#pone.0200106.ref034" target="_blank">34</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0200106#pone.0200106.ref035" target="_blank">35</a>].</p

Inversion effects.

<p>Inversion effects were evident both when considering whether an inverted face was recognized as a face (red) and when considering reaction times (yellow), i.e., longer reaction times to inverted than to upright faces. The latter type of inversion effect was much more frequent than the former. Overall, inversion effects of reaction times showed a median effect of 66 ms in our new stimulus set, and 79 ms in the original Mooney stimulus set (black solid lines). The right shows the stimuli with the most reliable/largest inversion effects for face recognition and reaction times, respectively. Original Mooney faces reprinted from [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0200106#pone.0200106.ref001" target="_blank">1</a>] under a CC BY license, with permission from the Canadian Psychological Association Inc., original copyright 1957.</p

Face and Mooney face stimuli.

<p><b>(A)</b> This greyscale image is easily perceived as a face although most visual information is covered by shadows. <b>(B)</b> A typical “Mooney” face. <b>(C)</b> An extremely easy “Mooney” face, devoid of cast shadows.</p

Frequency of stimuli perceived as face, upright or inverted.

<p>Most faces were correctly identified as faces by the majority of subjects when presented upright (green) both in our and in the original Mooney face set, but both stimulus sets also contain difficult stimuli that are only perceived as faces by a few subjects. Face inversion (blue) markedly reduced the number of ‘face’ responses. On the right are examples of easy and difficult Mooney faces from the upright and the inverted conditions, respectively. Original Mooney faces reprinted from [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0200106#pone.0200106.ref001" target="_blank">1</a>] under a CC BY license, with permission from the Canadian Psychological Association Inc., original copyright 1957.</p

Eye-tracking analyses.

<p>(A) Pattern of fixations/saccades revealed in relation to the “cannon” stimulus (left) and its underlying POI map (right). (B) Pooled fixations on all stimuli as a function of visibility for a subject performing the ascending (left) and one performing the descending protocol (right). (C) Average fixation spread (distance from image center). (D) Fixation count, normalized per subject. (E) Fixation duration. (F) Average local contour density (computed from POI map) in areas of 0.5° in diameter around explored locations corresponding to fixations on the dot stimulus. (G) Integrated dot displacement, computed as a sum of displacements of dots (in areas of 0.5° in diameter around each fixation) relative to the undeformed lattice. The sum runs over all fixation locations in the trial. Error bars represent s.e.m.</p

Psychometric curves, subjective and objective thresholds.

<p>Psychometric curves grouped by response type (A) and by verbal report accuracy (B) as a function of visibility (<i>g</i> value) and experimental condition (ascending and descending). (C) Thresholds for sigmoidal response curves corresponding to “Seen” (subjective) responses (left) and correct (objective) verbal responses (right). Error bars represent s.e.m.</p

Exploration time estimated by measuring reaction time as a function of response type in the two experiments.

<p>Error bars represent s.e.m.</p

Detection and recognition of individual objects.

<p>(A) Borders between “Nothing”/“Uncertain” (detection) and “Uncertain”/“Seen” (recognition) computed on individual objects, for the ascending (left) and descending (right) conditions. Error bars are s.e.m. (B) Average and SD of detection and recognition borders from (A) across all objects. (C) Individual object detection and recognition borders in the descending versus ascending condition.</p