Motion and Emotion Distracters on Basketball Shooting 1 Running head: MOTION AND EMOTION DISTRACTERS ON BASKETBALL SHOOTING Motion and Emotion Distracters: Effects on Basketball Free Throw Shooting Accuracy

In the present study we tested if background visual stimuli can impede accuracy of basketball free throw shooting. Actions are frequently found to resist illusions in the psychological literature, but most such studies only utilize reaching or pointing. Other research reports that emotional arousal can affect motor control. We projected images onto a basketball backboard, either continuous motion gradients to produce a sense of illusory movement, or provocative pictures to produce arousal. The moving stimuli varied in speed, type (dot or line), and direction. The emotionally arousing images varied in pleasantness. Our findings show that while there may be some systematic effects of background stimuli, there was not a significant general decrement in shooting accuracy. The findings suggest that background antics are not likely to have a notable impact on the free throw shooting accuracy of skilled players. More generally the findings provide further support for the robustness and independence of the perception-action system to resist distortion and distraction. Motion and Emotion Distracters on Basketball Shooting 3 Motion and Emotion Distracters: Effects on Basketball Free Throw Shooting Accuracy It is common practice for sports fans to attempt to disrupt the opposing team’s players in hopes of influencing game outcomes. These displays are commonplace, such as in when fans move exaggeratedly behind a basketball hoop with the hope of disturbing free throws. How realistic is the belief that such acts have any effect? In this study we investigated the possible detrimental effects of background visual stimuli on basketball free throw performance. In basketball, vision has been well examined. An aspect of vision pertaining to accuracy dubbed “quiet eye”, the amount of time spent fixated on the basket before a shot is taken, has been studied by a number of researchers (Vickers, 1996). Vickers, for example found that increased lengths of time spent focusing on the hoop prior to shooting was related to better performance. Similarly the effects of such factors as head and eye stabilization during movement have been researched (Ripoll, Bard, & Paillard, 1986). In addition there are a number of papers concerning other aspects of basketball such as the physics and dynamics of ideal shots and shooting dynamics (Brancazio, 1981; Hamilton & Reinschmidt, 1997). Studies concerning the effects of perceptual illusions on motor control have shown that participants experience perceptual distortion and have altered saccades, even when several forms of movement, such as grip aperture and endpoint accuracy, tend not to show similar distortions (Bernadis, Knox, & Bruno, 2005). Researchers have proposed that this discrepancy could be due to separate systems governing the use of such visual information for actions and perceptions, the dorsal and ventral systems. Of particular Motion and Emotion Distracters on Basketball Shooting 4 interest to the current study was work done by Smeets and Brenner (1995) on the effect of apparent background motion on apparent movement of a simulated spider. When the background moved, the spider’s apparent velocity across the screen was perceived as changing. Nevertheless the position of the spider at the end of the movement was accurately judged by participants. It is unlikely however, that the complex act of throwing a ball will show the same effects as directing a mouse cursor because some aspects of motion control, such as lifting force, are subject to disruption by illusions (Brenner & Smeets, 1996). Thus the results of the simulated spider study may not carry over to effects of aiming at a distant target. It is also important to consider evidence presented by Glover and Dixon (2001) that trajectory is most strongly influenced by illusions early in movement. As basketball free throws are only under the shooter’s direct control for a short period this could mean that effects will be present. Due to the combination of these factors it is difficult to say whether or not illusory effects are likely to be detrimental to accuracy on a free throw task. Furthering our attempts to uncover anything that will cause disrupted free throws, we investigated the potential effects of emotional arousal. Coombes, Janelle, and Duley (2005) found that motor error on a tracing task was higher after brief exposure to unpleasant versus pleasant visual stimuli. They also found tracing speed increased after repeated exposure to unpleasant versus pleasant stimuli. Others have found that emotionally charged imagery draws instant attention better than unemotional imagery when participants are distracted by another task (Carretie, Hinojosa, Martin-Loeches, Mercado, & Tapia, 2004). This could draw upon attentional resources, and in doing so inhibit function. It is within reason that emotional images could have a significant effect Motion and Emotion Distracters on Basketball Shooting 5 on motion control when presented during a free throw task. It is also a feasible concern for players at real sporting events, since stimuli such as crowd response could cause such emotional priming. In this study we utilized a variety of effects to distort perception. Continuous motion gradients were used to cause a sense of illusory movement and images formulated to cause arousal were presented in a highly observable manner. Both were projected onto the backboard to see if any effect could be produced. Our moving stimuli were varied in speed, type (dot or line), and direction in order to maximize our ability to find an effective motion pattern. Our emotionally arousing images were of both pleasant and unpleasant types to determine if either has an effect. Our hypothesis is that the presence of motion stimuli and emotional stimuli will affect shot accuracy (both distance off center and success rate) as compared to control trials with no stimuli projected on the backboard. We propose that that stimuli factors like visual element type, speed, direction, and emotional content have an impact on accuracy. Specifically we compare the effect of these variables on free-throw shooting by examining their effect on corresponding dependant variables, which included the percentage of cleanly made baskets, and the lateral and depth-wise deviation of the ball from the center of the hoop. Method Participants Eleven participants were involved in this study. 4 graduate students volunteered from a kinesiology lab and 7 undergraduate students were selected from the Arizona State University psychology 101 research pool and obtained credit for taking part in our Motion and Emotion Distracters on Basketball Shooting 6 study. No participants reported diagnosed motor problems or impaired or uncorrected vision. Materials The task was performed in the Arizona State University gymnasium utilizing a regulation basketball hoop with white backboard. Participants shot a junior-size basketball that was coated with retro-reflective tape for use with the motion capture system. All shots were made from the free throw line in the key for that hoop. An 8 camera Vicon motion capture system was used to judge the location of the ball. A video projector connected to a computer was used to project visual stimuli directly onto the backboard of the hoop. Design We used a series of single-factor within subjects analyses of variance (ANOVAs) and pairwise comparisons to examine the effects of all stimulus variables on free-throw shooting. As an initial test of our hypothesis, we examined the effect of trial type (emotion, motion, control) on accuracy. We followed with several individual factor analyses to explore differences in performance for the levels of each factor. We then proceeded with additional analyses to explore the differences in the levels of direction (7 levels: in and out, left and right, up and down, and random) and emotion (pleasant and unpleasant) using planned pairwise comparisons. Specifically, we predicted directional motion would bias the shots in a direction consistent with the motion, so we compared the lateral deviation in the position of the ball for lateral motion, and depth deviation for inward and outward motion, and overall accuracy for vertical motion. Motion and Emotion Distracters on Basketball Shooting 7 Stimuli Stimuli used were computer created moving dot fields, moving line patterns, and pleasant and unpleasant pictures. Basic dot and line fields moved up, down, left, and right. Also included were motion toward or away from the viewer by expanding dots or rings emanating from a center point to simulate motion down a tunnel. Also used were chaotic motion stimuli where dots or lines moved independently of one another in various directions and a blank white control. Pleasant emotion provoking stimuli were pictures of a kitten, a jungle waterfall, and a man and woman judged by lab members to be cute, calming, and attractive respectively. Unpleasant images consisted of an ugly dog, infected toenail, and a broken limb judged by lab members to be ugly, disgusting, and painful respectively. Figure 1: Schematic diagrams of the stimuli factors and levels. Measures Shot accuracy was measured, by a motion capture system, in variance from the location of the shooters’ average shot when a few inches above the basketball rim. Such Stimuli Motion Control Emotion Direction Speed Type Pleasant Unpleasant Up Down Left Right In Fast Slow Dot Line