When a rugby footballer sees himself (or herself) convert a try, the size of the goal subsequently seems wider.
Since this is the only dimension which changes perceptually, the task of scoring in this way is believed to get easier in future.
Today’s invention is a training aid based on this finding. The player wears a pair of goggles which can be electronically blacked-out very rapidly. A set of optical sensors detects the passage of the ball as it is first kicked.
A quick calculation by a computer to which they are connected can accurately predict whether or not a goal will be scored (taking into account cross-wind velocity, as necessary).
If the shot is off-target, the glasses are darkened so that the kicker’s task is never made more difficult by observing his failure.