# Driver Gaze Behavior Is Different in Normal Curve Driving and when Looking at the Tangent Point

## TL;DR

This study shows that drivers' gaze behavior differs when driving normally versus focusing on a tangent point, supporting models that predict visual strategies in curve driving.

## Contribution

The study provides empirical evidence supporting future path models over tangent point models in curve driving using detailed eye-movement analysis.

## Key findings

- Eye-movement patterns in normal driving differ from those when focusing on the tangent point.
- Horizontal gaze speed during OKN aligns with future path model predictions.
- OKN is not an involuntary reflex when drivers attempt to look at the tangent point.

## Abstract

Several steering models in the visual science literature attempt to capture the visual strategies in curve driving. Some of them are based on steering points on the future path (FP), others on tangent points (TP). It is, however, challenging to differentiate between the models’ predictions in real–world contexts. Analysis of optokinetic nystagmus (OKN) parameters is one useful measure, as the different strategies predict measurably different OKN patterns. Here, we directly test this prediction by asking drivers to either a) “drive as they normally would” or b) to “look at the TP”. The design of the experiment is similar to a previous study by Kandil et al., but uses more sophisticated methods of eye–movement analysis. We find that the eye-movement patterns in the “normal” condition are indeed markedly different from the “tp” condition, and consistent with drivers looking at waypoints on the future path. This is the case for both overall fixation distribution, as well as the more informative fixation–by–fixation analysis of OKN. We find that the horizontal gaze speed during OKN corresponds well to the quantitative prediction of the future path models. The results also definitively rule out the alternative explanation that the OKN is produced by an involuntary reflex even while the driver is “trying” to look at the TP. The results are discussed in terms of the sequential organization of curve driving.