Energetic and Motor Responses to Increasing Force Requirements

Suzanne H. Mitchell, Jasper Brener

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


The effects of increasing work (force) requirements on energy expenditure and response topography were examined in 7 rats pressing a beam to earn food. For the 1st 16 days, the force requirement was 5.52 × 10-2 N 5.625 g. This increased by 4.91 × 10-2 N 5 g every 7th session until Ss had experienced 10 upward shifts. Following the 54.57 × 10-2 N 55.625 g condition, the original criterion was reinstated. During the augmented phase, Ss maintained stable reinforcement rates across conditions by increasing the peak force of beam pressing. These higher forces, occurring within 20 reinforcements of changing the force criterion, were produced primarily by increases in the rate of change of force (ΔF/ΔT). Also, while the rate of work performed on the beam increased, the overall energy expenditure fell. In contrast to these rapid adjustments, reinstating the original 5.52 × 10-2 N 5.625 g criterion resulted in only gradual alterations in motor performance.

Original languageEnglish (US)
Pages (from-to)174-185
Number of pages12
JournalJournal of Experimental Psychology: Animal Behavior Processes
Issue number2
StatePublished - Apr 1991
Externally publishedYes

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Experimental and Cognitive Psychology


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