By TRAVIS DORSCH / Scienceblog.com

Athletes who are on a winning streak often claim that they perceive their targets to be bigger than they actually are. After a run of birdies, for example, golfers sometimes say that the cup appeared to be the size of a bucket, and baseball players who have a hit a few home runs say that the ball is the size of a grapefruit. Conversely, targets are often reported to be smaller than they actually are by athletes who are performing badly.

Research carried out in the past 5 years suggests that these are more than just anecdotes, and that performance in sports can actually affect perception. A new study by psychologists at Purdue University now lends more weight to this, by providing evidence that success rate in American football field goals affects how the size of the goal posts is perceived.

Jessica Witt and her colleagues have been investigating perception in athletes fro a number of years. Earlier work by this group of researchers has shown that apparent ball size is correlated with batting average in softball players, so that players who are performing better perceive the ball to be bigger, and that golfers who play better judge the hole to be bigger than those who do not play as well.  

For this new study, Witt collaborated with former National Football League player Travis Dorsch. Twenty-three participants were taken to an indoor football practice field, where they warmed up with three practice kicks. They were then asked to estimate how many kicks out of 10 they would score, and also to estimate the dimensions of the field goal posts, using a scaled-down adjustable model made out of PVC pipes (below left). Each participant then kicked 10 field goals, after which they were asked to make another estimate of the height and width of the posts, using the same apparatus.

It was found that participants who made 3 or more successful kicks perceived the goal to be bigger than it actually was, whereas those who scored 2 or less goals perceived it to be smaller. There was also a relationship between the subsequent perception of the goal posts and how the kicks were missed: participants who more frequently kicked the ball to the left or right of the target perceived the upright posts to be narrower, whereas those whose kicks tended to fall short of the goal, or to be too low, perceived the crossbar to be higher.

There are number of possible explanations for these findings. One is that there is a relationship between the participants' prediction of their success rate and their perception of goal size, so that those who predicted more successful kicks perceived the goal to bigger, but this was found not to be the case. Alternatively, there may have been pre-existing differences in the participants' perceptions of the goal posts, and the earlier studies of golfers and softball players had not ruled this out, because the participants had only been asked to estimate target size after performing the task. This time though, the participants were asked to make their estimates twice - once just before their 10 field goal kicks, and again immediately afterwards. The pre-kicking estimates of those who scored 2 kicks or less were no different from those who scored 3 or more, strongly suggesting that the differences in the second estimate of goal size were due to performance on the task.

This is the latest in a series of studies showing that our perceptions are grounded firmly in our actions. Witt's group has previously demonstrated that perceptions of goal size in golfers and softball players are apparently affected by performance. Other researchers have shown that perception is also influenced by the amount of effort required to perform an action. A location seems further away when one has to walk uphill to reach it, or if one is tired or in pain during the walk, and hills look steeper when one is carrying a heavy backpack. Similarly, objects that are just out of reach are perceived to be closer when one is holding a tool that extends reach, while those that are positioned so that they are difficult to grasp are perceived as being further away.

All of these studies show that perception does not merely involve reconstructing the geometry of one's environment from visual information. Rather, our perceptions seem to be firmly grounded in, and strongly influenced by, the abilities, intentions and efforts of the perceiver. This may be because we view the environment in terms of energy costs, and plan our actions accordingly. Thus, a tired walker who perceives a hill to be steeper than it actually is will walk more slowly, and an athlete who perceives a target to be bigger will need to expend less energy and attention. Conserving energy is vital for survival, so such an adaptation would confer an important evolutionary advantage.

About the author: Travis Dorsch is a staff member with the Ray Guy kicking Academy. He was All-American kicker and punter at Purdue and won the Ray Guy Award. He is presently in a doctorate program at Purdue.