The Wimbledon Tennis Championships are currently underway, showcasing not only the amazing skills and athleticism of the world top ranked players, but also their target detection and visual tracking abilities. The ability to judge the speed, trajectory and even the amount of spin on the ball are important to ensure accurate shot selection and reduce unforced errors.
But is this all reliant on just vision?
It’s quite easy to imagine that playing a game of tennis blind-folded would be extremely difficult. You are not able to see the approach of the ball, or watch the racket as you swing it through the air to make contact. In contrast, you might think playing tennis without the ability to hear would be relatively easy. It turns out this is not the case, even with a mainly visually oriented sport where the player is always facing their opponent and in continuous visual contact with the ball, simply seeing the ball may not be enough.
Given that human reactions to visual stimuli can be over 20ms longer than those to auditory stimuli, hearing the ball may enable faster reactions times. A huge advantage in a sport where a top serve can be over 230 km/hr, meaning even the tiniest fraction of a second can make the difference between a successful return of serve or an ace by your opponent.
This recent paper by Spence et al, demonstrates the need for auditory cues to accurately anticipate the length of the trajectory of an opponent’s tennis stroke. When the auditory cues were manipulated to have a higher sound intensity the predicted trajectory lengths were significantly longer than normal sounds or those manipulated to have a lower sound intensity. Additionally, it has been shown that when the sound of the ball hitting the racket is masked with a competing sound, reaction time are decreased and decision errors increase. (Sinnett and Kingstone, 2010)
Perhaps partly explaining why some of the best tennis players either grunt or shriek loudly when they strike the ball.
So, what does this all mean for our hoverflies and their visual abilities? Can auditory cues reduce reaction times and enhance responses to visual cues? Could the sound of an approaching wasp, for instance, enhance escape responses to looming stimuli? Or do other sensorial cues play an important role in reinforcing or enhancing insect vision?