Action outcome probability influences the size of the head-fake effect in basketball

Both kinematic and contextual information (e.g., action outcome probability) play a significant role in action anticipation. However, few researchers have examined the reciprocal influence of the two types of information and fewer still have investigated this issue for deceptive actions in sports. In the present study, we investigate the impact of action outcome probability on the processing of deceptive kinematic cues for the head fake in basketball. We manipulated the probability of the action outcome to either pass the ball to the left or to the right side (i.e., 75%, 50%, 25%) and examined how this contextual information affected the influence of head orientation on pass direction judgments. Outcome probability information was either provided explicitly (Experiment 1) or implicitly (Experiment 2). Both experiments indicated an increased head-fake effect with increasing outcome probability. Moreover, the bias to respond in line with the player's head direction increased linearly with outcome probability. Also, discriminability between deceptive and genuine actions was poorer for high outcome probability (75%) associated with head orientation than for the 25% and 50% values. Last, a stronger response bias toward the higher probability side for deceptive trials than for genuine trials was only significant when the outcome probability information was processed implicitly in Experiment 2. The results of this study fit well with recent literature on contextual information in action prediction and are discussed in light of confirmation bias and signal detection theory.