Reinforcement omission in concurrent fixed-interval and random-interval schedules

Taku Ishii, Takayuki Sakagami

Research output: Contribution to journalArticle

2 Citations (Scopus)


The present experiment examined overall and local effects of omission of reinforcers in a choice situation. Pigeons' key-pecking responses were reinforced under concurrent fixed-interval and random-interval schedules of food presentation. After some weeks of baseline sessions in which the probability of reinforcement was 1.00, approximately 25% of food presentations from the fixed-interval schedule were omitted and replaced by timeout periods. In such omission sessions, the overall relative rates of responding to the fixed-interval schedule became lower than those in the baseline sessions. On the other hand, when relative rates of responding to the fixed-interval schedule in the omission sessions were calculated separately for fixed-interval cycles preceded by timeout periods and those preceded by food presentations, the relative rates in the former type of fixed-interval cycles were higher than those in the latter type for three out of four pigeons. These results mean that relative rates of responding cannot always be regarded as reflecting a relative value of an alternative, and that the overall effect of the omission of fixed-interval reinforcers is not reducible to the local effect of omission.

Original languageEnglish
Pages (from-to)334-341
Number of pages8
JournalBehavioural Processes
Issue number3
Publication statusPublished - 2007 Mar 1



  • Choice behaviour
  • Key peck
  • Pigeon
  • Reinforcement schedule

ASJC Scopus subject areas

  • Animal Science and Zoology
  • Behavioral Neuroscience

Cite this