Slow motion increases perceived intent.

To determine the appropriate punishment for a harmful action, people must often make inferences about the transgressor's intent. In courtrooms and popular media, such inferences increasingly rely on video evidence, which is often played in "slow motion." Four experiments (n = 1,610) involving real surveillance footage from a murder or broadcast replays of violent contact in professional football demonstrate that viewing an action in slow motion, compared with regular speed, can cause viewers to perceive an action as more intentional. This slow motion intentionality bias occurred, in part, because slow motion video caused participants to feel like the actor had more time to act, even when they knew how much clock time had actually elapsed. Four additional experiments (n = 2,737) reveal that allowing viewers to see both regular speed and slow motion replay mitigates the bias, but does not eliminate it. We conclude that an empirical understanding of the effect of slow motion on mental state attribution should inform the life-or-death decisions that are currently based on tacit assumptions about the objectivity of human perception.

Predicting premeditation: future behavior is seen as more intentional than past behavior.

People's intuitions about the underlying causes of past and future actions might not be the same. In 3 studies, we demonstrate that people judge the same behavior as more intentional when it will be performed in the future than when it has been performed in the past. We found this temporal asymmetry in perceptions of both the strength of an individual's intention and the overall prevalence of intentional behavior in a population. Because of its heightened intentionality, people thought the same transgression deserved more severe punishment when it would occur in the future than when it did occur in the past. The difference in judgments of both intentionality and punishment was partly explained by the stronger emotional reactions that were elicited in response to future actions than in response to past actions. We consider the implications of this temporal asymmetry for legal decision making and theories of attribution more generally.