Abstract: A system for generating a reward when a shopping cart is returned to a holding pen. The entrance to the pen is defined by a pair of spaced apart pedestals containing a light source projecting on photo diodes. When the light on the diodes is interrupted by the upright strands of a cart, a set of pulses is generated and counted. The counts are fed to decision logic which control the reward generator. The reward generator is rendered operable only if the decision logic determines that a shopping cart has been pushed between the pedestals into the holding pen.