Fig 1.
Definition of areas of interest (AOI) and experimental procedure.
(A) AOI defined based on their semantic meaning in the driving task. (B) Experimental procedure: Each trial comprises a baseline period of five fixations and the task interval that starts with the deceleration of the car in front of the ego-car (grey). The task is split into the period before lane change, between trial onset and changing onto the left lane (blue arrow and marker), and the period after lane change, between changing onto the left lane and changing back onto the right lane (red arrow and marker).
Fig 2.
Schematic illustration of AIS estimation and relationship with other information-theoretic measures.
(A) Schematic illustration of relationship between AIS (blue box), conditional entropy of the next fixation given the past state (orange box) and the joint entropy between past state and next fixation (grey box). For , the conditional entropy is equivalent to the GTE. (Adapted from [38]). (B) Schematic illustration of the non-uniform embedding (modified from [14]). The blue box indicates all past variables up to a maximum lag, lmax, that are considered during the optimization of the past state for AIS estimation. The red marker indicates the next fixation, Xt, and blue markers indicate the variables selected by the optimization that comprise the optimized past state,
.
Fig 3.
Proportion of fixations and mean fixation duration.
(A) Relative fixation proportions for each AOI across all participants in the three different trial periods (LC = lane change). (B) Distribution of mean fixation duration across participants for the three trial periods and two levels of difficulty including (whiskers indicate 95% confidence intervals). (C) Mean fixation duration per participant for each trial period (error bars indicate 95% confidence intervals). (D) Mean fixation duration per participant for both difficulty levels (error bars indicate 95% confidence intervals).
Fig 4.
Selected past variables per participant.
Lags, l, of past variables used for AIS estimation as identified by the estimation algorithm for each participant.
Fig 5.
Mean values of LGTE (orange), LAIS (blue), and joint entropy (gray) as a function of trial period.
Mean per trial period for participants with lag l > 1 for (A) LGTE, (B) LAIS, (C) joint entropy between next fixation and past fixation at t − 1 (fixations used for LGTE estimation), (D) joint entropy between next fixation and past fixation at t − l (fixations used for LAIS estimation). Mean per trial period for participants with lag l = 1 for (E) LGTE, (F) LAIS, (G) joint entropy between next fixation and past fixation at t − 1 (fixations used for LGTE estimation), (H) joint entropy between next fixation and past fixation at t − l (fixations used for LAIS estimation). Error bars indicate the standard error of the mean.
Table 1.
Linear mixed-effect model results for normalized LAIS and LGTE estimates for participant group with past state l > 1.
Table 2.
Linear mixed-effect model results for mean normalized LAIS and LGTE estimates for participant group with past state l = 1.
Fig 6.
Predicted values of mean LGTE (orange) and mean LAIS (blue) by linear mixed-effects model (LMEM).
Error bars indicate confidence intervals. (A) Mean LGTE values normalized by mean joint entropy for l > 1, (B) mean LAIS values normalized by mean joint entropy for l > 1, (C) mean LGTE values normalized by mean joint entropy for l = 1, (D) mean LAIS values normalized by mean joint entropy for l = 1.