The points display the mean proportion of dwell time and first fixations directed towards objects of four semantic features. The error bars indicate 1 s.e.m. Please note that each age bin spans two years. Due to space constraints, only every second tick mark is labelled. A total of 6,720 participants were included in the analysis; for a more detailed distribution of participants across age groups, please refer to Fig. 2 . Semantic categories are indicated by colours, as shown in the key. The lines show the corresponding best-fitting polynomials. In c and d , the horizontal lines above the plots indicate the level of evidence for a given bin to be part of a broad linear change via shades of grey, as shown in the key (sliding window analysis; see main text and Methods ). Red shading marks age bins with lower sensitivity to developmental changes, which were disregarded for curve fitting ( n < 90 per bin). Panels a and b show the trajectories for all features in a single plot for comparisons of scale.
