Reaction Times

<p>Reaction times before and after training for Experiments 1 (A) and 2 (B). Error bars are plus or minus the SEM.</p

ROIs

<p>Functional activation maps for one subject showing the early retinotopic ventral (V1, V2, VP, and V4) and dorsal (V1, V2, V3, and V3a) areas and the LOC subregions. Functional activations (color-maps) are superimposed on flattened cortical surfaces of the right and left hemispheres. A, anterior; CoS, collateral sulcus; ITS, inferior temporal sulcus; OTS, occipitotemporal sulcus; P, posterior; STS, superior temporal sulcus.</p

Relationship between Psychophysical and fMRI Learning Effects

<p>fMRI data and the corresponding psychophysical response for low-salience (A) and high-salience (B) shapes. For each individual subject, we plotted a behavioral learning index (percent correct for trained minus percent correct for untrained stimuli) and an fMRI learning index (percent signal change for trained minus percent signal change for untrained stimuli) after training. Positive values indicate stronger responses for trained than untrained shapes, whereas negative values indicate lower responses for trained than untrained shapes. For low-salience shapes the regression analysis was significant in early visual areas (V1: <i>r</i> = 0.62, F_1,21 = 13.65, <i>p</i> = 0.001; V2: <i>r</i> = 0.42, F_1,21 = 6.65, <i>p</i> < 0.05; Vp: <i>r</i> = 0.50, F_1,21 = 7.62, <i>p</i> = 0.01; V4: <i>r</i> = 0.50, F_1,21 = 8.91, <i>p</i> < 0.01) and the LOC subregions (LO: <i>r</i> = 0.57, F_1,21 = 9.84, <i>p</i> < 0.01; pFs: <i>r</i> = 0.51, F_1,21 = 7.18, <i>p</i> = 0.01). For high-salience shapes the regression was significant only in the LOC subregions (LO: <i>r</i> = 0.56, F_1,15 = 6.69, <i>p</i> < 0.05; pFs: <i>r</i> = 0.61, F_1,15 = 8.58, <i>p</i> = 0.01) but not in the early visual areas (V1: <i>r</i> = 0.17, F_1,15 < 1, <i>p</i> = 0.51; V2: <i>r</i> = 0.25, F_1,15 < 1, <i>p</i> = 0.34; Vp: <i>r</i> = 0.28, F_1,15 = 1.27, <i>p</i> = 0.27; V4: <i>r</i> = 0.15, F_1,15 < 1, <i>p</i> = 0.56).</p

Behavioral Data during Training Sessions

<div><p>Psychophysical data (percent correct) during the three training sessions. Data are shown for trained and untrained shapes in which the observers were tested without feedback at the end of each training session. Statistical analysis of the data showed that the observers' performance improved for trained, but not untrained, shapes across training sessions.</p> <p>(A) In Experiment 1, no significant differences between trained and untrained stimuli were observed for session 1 (F_1,20 = 1.66 , <i>p</i> = 0.21) but increasing differences were observed for sessions 2 (F_1,20 = 19.57, <i>p</i> < 0.001) and 3 (F_1,20 = 47.79, <i>p</i> < 0.001).</p> <p>(B) Similarly, in Experiment 2, a significant effect (F_1,14 = 27.30, <i>p</i> < 0.01) of familiarity (trained vs. untrained shapes) was observed across training sessions.</p></div

Results for Experiment 1

<p>Psychophysical data (A) and fMRI responses obtained during the scanning sessions before (B) and after (C) training. Error bars indicate the SEM across subjects. Significant differences are indicated by asterisks. (A) Psychophysical data (percent correct) are shown for trained and untrained shapes in the tests before and after training. Normalized fMRI responses across subjects for trained and untrained shapes before (B) and after (C) training across the LOC subregions and the early ventral areas. Normalized fMRI responses were computed by subtracting the mean signal (percent signal change from fixation baseline) across conditions, sessions, and ROIs from the signal in each condition per subject and adding the overall average across conditions, sessions, ROIs, and subjects. These normalized fMRI responses indicate differences across conditions independent of the variability in the fMRI signal across subjects, scanning sessions, and ROIs.</p

Stimuli

<p>Examples of symmetrical and asymmetrical low- and high-salience stimuli.</p

Results for Experiment 2

<p>Psychophysical data (A) and fMRI responses obtained during the scanning sessions before (B) and after (C) training. Error bars indicate the SEM. Significant differences are indicated by asterisks. (A) Psychophysical data (percent correct) for trained and untrained shapes in the tests before and after training. Normalized fMRI responses across subjects for trained and untrained shapes before (B) and after (C) training across the LOC subregions and early ventral areas.</p

Summary of Results

<p>fMRI learning effects for low-salience (Experiment 1) and high-salience (Experiment 2) shapes indicated by subtracting the fMRI responses for untrained from those for trained stimuli in the post-training session in each experiment. Error bars are plus or minus the SEM. Positive values indicate stronger fMRI responses for trained stimuli, whereas negative values indicate stronger fMRI responses for untrained stimuli.</p

Infant fMRI data

Infant fMRI dat

Significance values (<i>p</i>) for difference in classification ages.

<p>Significance values (<i>p</i>) for difference in classification ages.</p