Kenneth H. Brookshire

Distilled Water and Tap Water as Factors in Taste Preference Experimentation

Albino rats were permitted to drink either distilled water or tap water from two bottles. Animals with prior experience with distilled water in the home cage showed a consistent preference for distilled water which increased over test sessions; Ss having prior experience with tap water did not show statistically reliable preference behavior. Amount of water deprivation during the test session and length of test session were not significant variables. It was concluded that previous results showing a preference for tap water reflect the operation of several variables including prior experience, but the present experiment casts doubt on interpretations, suggesting that tap water is in some general way more palatable or that tap water and distilled water may be equated when interpreting experiments on taste preference.

Apomorphine-induced conditioned aversion to a novel food

Rats were permitted to ingest both a novel and a familiar substance prior to injection with apomorphine hydrochloride (a nausea-producing drug) or isotonic saline. Subsequent 2-choice preference tests showed that apomorphine produced a conditioned aversion to the novel substance, but only with the more palatable of the two novel substances employed.

Acquisition and retention of conditioned taste aversions as a function of the taste quality of the CS

Abstract Rats were given three-choice preference tests involving saccharin, NaCl, and citric acid. One substance was familiar to S, a second was novel, and a third (CS) has been associated with gastrointestinal illness. Conditioned aversions were acquired and retained when the CS was saccharin or NaCl but not when it was citric acid. In a second experiment, using a simpler two-choice test, a conditioned taste aversion to citric acid again could not be detected. Together, the results suggest that CS adequacy may vary as function of taste quality.

Formation and retention of conditioned taste aversions and UCS habituation

In Experiment I rats received 10 consecutive daily injections of either apomorphine hydrochloride or NaCl followed by 4 days of saccharin solution exposure paired with apomorphine or NaCl injections. Relative consumption of saccharin solution and water during conditioning indicated that preconditioning apomorphine UCS habituation retarded acquisition of a conditioned saccharin aversion. In Experiment II rats received 6 days of saccharin solution exposure paired with injections of either apomorphine hydrochloride or NaCl, then 10 daily injections of either apomorphine hydrochloride or NaCl, followed by 4 days of saccharin preference testing (no drug injections). Postconditioning apomorphine UCS habituation did not interfere with retention of saccharin aversion acquired in initial conditioning phase. These results showed that novelty of UCS is crucial in acquisition of but not retention of conditioned taste aversions.

Conditioned fear training and later avoidance learning in the goldfish

In Experiment 1 goldfish showed early facilitation of one-way avoidance behavior following conditioned fear training. In a second experiment, two-way avoidance behavior was studied. An interference effect emerged but only under conditions suggesting a fatigue explanation.

Shuttle box avoidance learning and epinephrine

Rats were trained on a two way shuttle avoidance response under one of two doses of epinephrine or placebo conditions. No effect of the hormone was found in female rats, while males learned less effectively under high doses of the hormone. No facilitation of avoidance learning was found at either dosage.

Conditioned Fear in the Fish

Paradise fish, macropodus opercularis, were given inescapable shocks in the black side of a two-compartment box. Following training they showed acquisition of a target-striking instrumental response which permitted them to escape from the black compartment to a white compartment. Non-shocked control Ss also showed evidence of learning, probably based on an exploratory drive, but their behavior was far less persistent than that of the experimental group. The results are compared with those of other studies, on both the fish and mammals, which have investigated the effects of conditioned fear training, and some theoretical implications are drawn.

Conditioned taste aversions as a function of the number of CS-US pairs

Rats were given two-choice water-saccharin preference tests after saccharin had been paired with apomorphine hydrochloride for 1, 2, 4, 8, or 16 trials. The results indicated that the conditioned aversion is quite pronounced after only two trials and that suppression of single stimulus consumption of the CS substance during successive conditioning trials is not perfectly related to the preference data.

Effect of epinephrine on acquisition of conditioned fear

Abstract In two separate experiments it was shown that injected epinephrine had no effect on the acquisition of conditioned fear. In both experiments, fear conditioning (and epinephrine injections) were separated in time from behavioral tests designed to measure fear acquisition, thus precluding confounding of results by possible side effects of the hormone on performance. Experiment 1 showed, specifically, that epinephrine did not affect suppression of an appetitive response by a CS associated with shock; Experiment 2 indicated that epinephrine did not affect escape reaction to a CS associated with shock.

CS-US interval and conditioned fear facilitation of shuttlebox avoidance learning in the goldfish

Goldfish were given 40 Pavlovian fear conditioning trials and then were trained on a shuttlebox avoidance task under either a 10-sec or a 30-sec CS-US interval. When compared with unstimulated control Ss, fear-conditioned fish showed facilitation of avoidance responding for the 30-sec, but not for the 10-sec, interstimulus interval.