ACQUISITION OF LEVER-PRESS RESPONDING WITH DELAYED CONSEQUENCES IN RATS: IS A MINUTE TOO LONG?

Abstract

Sixteen water-deprived rats were exposed to 30 4-hr sessiens in which responsas en ene lavar prnduced water undar a rasatting dalay nf 60s and responses en a second lavar cancelad any schaduled water dalivarias. Pravious studias haya damonstratad response acquisitinn within ene sassion undar similar prncedures with shorter (e.g., 30-s) dalays, but there was no avidanca nf censistent response acquisitinn in tha present study, Althnugh 1 0 rats emittad savaral mora responsas en tha lavar that predUcad water than en fha lavar that cancelad water daliveries en tha first day, and raceivad mere than 10 watar delivarias, this pattarn enly parsisted ter two rats. Nene of tha rats that failad te acquire the response during tha ¡nitial sessien acquirad tha response ovar subsequant sassions. Thase findings suggast that raspending is net nacassarily strangthanad by pretractad axpnsura te rasettEng delay arrangemants and that pattarns of raspnnding observad en initial axpesura te such arrangamants may diffar substantially frem thesa observad subsaquantly.