, Volume 76, Issue 3, pp 286–290 | Cite as

Drug effects on discrimination performance at two levels of stimulus control

  • Charles Ksir
  • Barbara Slifer
Original Investigations


The effects of several doses of d-amphetamine, chlordiazepoxide (CDP), chlorpromazine (CPZ), LSD, pentobarbital, and scopolamine were examined in rats trained to respond to the brighter of two keys. On each of the 100 trials during a daily session, the rat pressed the key that was brighter (correct key) and received a food pellet, or pressed the incorrect key and terminated the trial without food, or pressed neither key for 10 s, allowing the trial to terminate. Within a session, trials were mixed randomly such that on 50 trials the incorrect key was not lit (easy trials,) and on 50 trials the incorrect key was dimly lit (difficult trials). Amphetamine (0.5–2.0 mg/kg) reduced percent correct responses, with a greater effect of difficult than on easy trials. CDP (4.0–16.0 mg/kh) and pentobarbital (2.0–16.0 mg/kg) reduced percent correct responses on the difficult trials at the highest doses tested. Scopolamine (0.12–1.0 mg/kg) reduced both percent correct (more so on the difficult trials) and percent of trials on which a response was made, in a dose-related fashion. CPZ (1.0–4.0 mg/kg) reduced trial responding at 2.0 and 4.0 mg/kg and reduced percent correct on the difficult trials at 4.0 mg/kg. LSD (0.08–0.32 mg/kh) did not significantly alter behavior in this study.

Key words

Amphetamine Chlordiazepoxide Chlorpromazine LSD Pentobarbital Scopolamine Behavior Rats 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Aghajanian GK, Foote WE, Sheard MH (1970) Action of psychotogenic drugs on single midbrain raphe neurons. J Pharmacol Exp Ther 171:178–185Google Scholar
  2. Appel JB, Dykstra LA (1977) Drugs, discrimination and signal detection theory. In: Thompson T, Dews PB (eds) Advances in behavioral pharmacology, Vol 1. Academic, New York, pp 140–166Google Scholar
  3. Eckerman DA, Gordon WA, Edwards JD, MacPhail RC, Gage MI (1980) Effects of scopolamine, pentobarbital and amphetamine on radial arm maze performance in the rat. Pharmacol Biochem Behav 12:595–602Google Scholar
  4. Frontali M, Amorico L, De Acetis L, Bignami G (1976) A pharmacological analysis of processes underlying differential responding: A review and further experiments with scopolamine, amphetamine, lysergic acid diethylamide (LSD-25), chlordiazepoxide, physostigmine, and chlorpromazine. Behav Biol 18:1–74Google Scholar
  5. Grilly DM, Genovese RF, Nowak MJ (1980) Effects of morphine, d-amphetamine, and pentobarbital on shock and light discrimination performance in rats. Psychopharmacology 70:213–217Google Scholar
  6. Hasegawa Y, Ibuka N, Iwahara S (1973) Effects of chlordiazepoxide upon successive red-green discrimination responses in Japanese monkeys, Macaca fuscata. Psychopharmacologia 30:89–94Google Scholar
  7. Heise GA, Lilie NL (1970) Effects of scopolamine, atropine, and d-amphetamine on internal and external control of responding on non-reinforced trials. Psychopharmacologia 18:38–49Google Scholar
  8. Hirschhorn JD, Winter JC (1971) Mescaline and lysergic acid diethylamide (LSD) as discriminative stimuli. Psychopharmacologia 22:64–71Google Scholar
  9. Iwasaki T, Ezawa K, Iwahara S (1976) Differential effects of chlordiazepoxide on simultaneous and successive brightness discrimination learning in rats. Psychopharmacology 48:75–78Google Scholar
  10. Ksir C (1975) Scopolamine and amphetamine effects on discrimination: Interaction with stimulus control. Psychopharmacologia 34:127–134Google Scholar
  11. Ksir C, Nelson S (1977) LSD and d-amphetamine effects on fixedinterval responding in rats. Pharmacol Biochem Behav 6:269–272Google Scholar
  12. Laties VG, Weiss B (1966) Influence of drugs on behavior controlled by internal and external stimuli. J Pharmacol Exp Ther 152:388–396Google Scholar
  13. McKearney JW (1970) Rate-dependent effects of drugs: Modification by discriminative stimuli of the effects of amobarbital on schedulecontrolled behavior. J Exp Behav. 14:167–175Google Scholar
  14. McKearney JW, Barrett JE (1978) Schedule-controlled behavior and the effects of drugs. In: Blackman DE, Sanger DJ (eds) Contemporary Research in Behavioral Pharmacology, Plenum, New York, pp 1–68Google Scholar
  15. McKim WA (1981) Rate-dependency: A nonspecific behavioral effect of drugs. In: Thompson T, Dews PB, McKim WA (eds) Advances in Behavioral Pharmacology, Vol 3. Academic, New York, pp 61–73Google Scholar

Copyright information

© Springer-Verlag 1982

Authors and Affiliations

  • Charles Ksir
    • 1
  • Barbara Slifer
    • 1
  1. 1.Department of PsychologyUniversity of WyomingLaramieUSA

Personalised recommendations