Fig. 4. Single subject correlations.

To verify that the negative gradient of duration-tracking accuracy is not driven by differences between subjects (i.e. to verify that tracking accuracy and position along the ventral stream are correlated within subjects, rather than that subjects with more posterior coverage have generally higher duration-tracking), we fitted a mixed-effect linear regression model to the single-trial duration-tracking data. The binomial result of each trial in each electrode (accurate/inaccurate response duration) was used as the dependent variable, and either the electrodes’ onset response latency, or its posterior-anterior position was used as an independent variable, with random intercepts and slopes for each subject and random intercepts for individual trials. The continuous measures of latency and anatomical position were used as the independent variables for the analysis of electrodes across all visual areas rather than region labels, because there were not sufficient data for the model to converge with an ordinal independent variable. The results indicated a significant fixed effect for both latency and position for all responsive electrodes, all right-hemisphere IT electrodes, all right-hemisphere face-selective electrodes, and all right-hemisphere object selective electrodes. Left panel: data points for all responsive electrodes divided by subject, and subject-specific regression lines. Right panel: same for right-hemisphere IT face-selective electrodes. Mixed-effects analysis was performed using R (www.r-project.org) with the lme4 software package.