Effect of contingent and non-contingent social reinforcement on the cooperative play of a preschool child.

One preschool child played in a room with toys and an adult. The adult gave praise only when the child shared or helped. Later the adult gave friendly comments at random times. The researchers flipped these two conditions back and forth four times to see which one made cooperation grow.

They measured how many seconds the child spent in cooperative play during each session.

Praise tied to the exact moment of sharing quickly doubled cooperative play. Random nice talk did nothing. When praise stopped, cooperation dropped. When praise returned, cooperation rose again.

The pattern repeated across all four phases, showing the praise, not luck, drove the change.

Bigby et al. (2009) ran a near-copy of this study 40 years later. They added a choice test and found 7 of 8 preschoolers picked the contingent praise schedule over free attention, backing the 1968 claim that kids value earned praise.

Schwarz et al. (1970) and Striefel et al. (1974) stretched the same tactic to children with intellectual disability and behavior disorders. Cooperation or peer interaction rose in each group, proving the rule crosses diagnostic lines.

Finney et al. (1995) and Brown et al. (1988) later bundled the contingent praise into group contingencies. Their preschoolers with autism and typical peers boosted social bids even more, showing the 1968 seed grew into classroom-wide packages.

You already have the strongest tool in your pocket: immediate, specific social praise. Use it the moment a client hands over a toy, helps a peer, or waits a turn. Skip vague “good job” chatter that isn’t tied to a behavior. This tiny shift keeps cooperation high without extra materials or tokens.