The effects of fixed ratio values on concurrent mand and play responses.

Bernstein et al. (2009) worked with three children who had developmental delays. The team set up two side-by-side tasks: asking for items (mands) and playing with toys. Each task had its own reward rule. Play stayed on an FR1 rule: one play move earned one token. The mand task moved from FR1 to FR10: the child now had to ask ten times to earn the same token.

The goal was to see if kids would keep asking while play got richer by comparison.

All three children started playing more once the mand schedule thickened to FR10. Their requests stayed the same or even rose. No child stopped asking for items when the price went up.

In short, lean rewards for mands made play look like a bargain, so play grew.

Greer et al. (2016) reviewed 25 FCT cases and showed that thinning schedules works when you add clear S-delta cues. Haven’s study is one of the early single cases that Greer’s team counted, proving a mand can live on FR10 while play stays at FR1.

Ramirez et al. (2025) pushed the idea further. They started kids on a fixed-lean 60 s/240 s multiple schedule right after FCT. Two of three kids kept low problem behavior and solid manding, matching Haven’s FR10 finding but using time-based instead of response-based thinning.

Hawkins (1979) saw lab rats lock onto the richer side when concurrent ratio differences got large. Haven turned that basic finding into an applied tool: make play the "rich" side and kids will play more without dropping their requests.

You can safely thin mand reinforcement to FR10 while keeping play at FR1. Play jumps, mands hold, and you spend fewer tokens on requests. Try it next time a child’s play skills need a boost but you still want independent asking.