A 2 by 5 design was utilized to investigate two levels of reward magnitude under conditions including the administration of nonrewarded placements to rats in the start box, mid box, and goal box of a straight runway, with two conditions used as controls for the latent extinction effect. High reward Ss showed faster recovery of start times under partial reinforcement but did not differ from low reward Ss in a prior stage of 100% reward. Nonplacement control Ss displayed faster recovery under partial reward than did Ss in the latent extinction conditions.