Effects of driving anger on driver behavior - Results from naturalistic driving data

- Anger resulted in more frequent violations but not in more frequent driving errors.
- Anger created danger due to willful behaviors, not because of cognitive overload.
- Not anger alone, nor combined with a conversation, increased the error frequency.
- Only anger in response to a thwarted driving goal increased the violation frequency.
- Severe anger was accompanied by more violations compared to slight or marked anger.

There is a positive relationship between driving anger and near-crash or crash risk. However, it remains unclear if anger in fact contributes to traffic accidents and whether this happens due to cognitive overload or aggressive driving behaviors. This study investigated how anger affects driving behavior based on naturalistic driving data from the second Strategic Highway Research Program (SHRP 2). Ten-minute trip segments were analyzed in which drivers exhibited anger with regard to driving errors, violations, and aggressive expressions. This data was compared to a matched baseline consisting of the same drivers not exhibiting anger. Results showed that anger resulted in more frequent aggressive driving behaviors but did not increase driving error frequency. Anger consequently creates danger due to deliberate behaviors rather than because of cognitive overload. In congruence with this finding, only anger triggered by threats, provocations, and frustrations increased the frequency of deliberate infringements. In contrast, anger due to having conflicts with someone on the phone or with a passenger was not linked to any type of aberrant driving behavior. Finally, severe displays of anger were accompanied by more violations as compared to slight or marked anger.

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