Preferences for tastes paired with recovery from thiamine deficiency in rats: Appetitive conditioning or learned safety?

Conducted a study of 80 male Sprague-Dawley rats to investigate earlier findings that rats develop learned preferences for flavors paired with recovery from vitamin deficiencies. Results show that thiamine deficient Ss preferred flavors paired with recovery from deficiency to other familiar flavors, suggesting that part of the preference for flavors paired with recovery was the result of appetitive conditioning. Data are discussed in relation to "learned safety," specific hungers, illness-induced neophobia, and other phenomena in the taste-aversion literature. (16 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conditioned preferences in the rat with an unnatural need state: Morphine withdrawal.

Placed 30 morphine addicted and 15 nonaddicted female albino rats on a 21-day conditioning regimen which involved the daily alternation of access to either water, sucrose-octa-acetate (SOA), or no liquid for 1 hr. The addicted Ss received injections of morphine after either the SOA sessions or the no-liquid sessions. Nonaddicted Ss were injected with morphine after the SOA sessions. Following the last injection, Ss were given a 2-bottle preference test between SOA and water. Results show that the addicted Ss that received morphine-SOA pairings had an increased preference for SOA, whereas the nonaddicted Ss showed a decrease in SOA preference after the same conditioning treatments. Addicted Ss that received the morphine injections on the no-liquid days showed no change in SOA preference. (21 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reversal of innate aversions: Attempts to induce a preference for chili peppers in rats.

Although humans frequently develop preferences for innately unpalatable bitter or irritant substances, such preferences are extremely rare in animals. An attempt was made to understand the nature of this difference by 5 experiments with Charles River albino rats, using chili pepper as the unpalatable substance. In parallel with major aspects of the human experience with chili pepper, Ss were exposed to it as a flavoring in all their food for periods up to 11 mo from birth without significant preference enhancement. Gradual introduction of chili into the diet also had no effect, nor did poisoning and safety experiences designed to teach Ss that only chili-flavored foods were safe to eat. Seven pairings of chili-flavored diet with prompt recovery from thiamine deficiency did significantly attenuate the innate aversion and may have induced a chili preference in at least 1 case. Extensive experience with chili did not reliably make Ss much less sensitive to its oral effects. The only reliable way to eliminate chili aversion in rats is to destroy their chemical irritant sense, which was accomplished in 1 group. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Enhancement and retardation of discrimination learning in chicks after exposure to the discriminanda.

Used an imprinting procedure to expose groups of Ross domestic chicks (N = 57) to 1 or 2 moving objects on Days 1-5 after hatching for a total of 30 or 100 min. From Day 8-12 Ss were given a discrimination learning task. Ss exposed to 1 of the discriminanda learned the task in fewer trials than Ss exposed to neither. However, Ss that had been exposed to both stimuli took many more trials to reach criterion than Ss that had seen neither in the imprinting situation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Transfer of a mnemonic keyword strategy at two age levels.

80 12- and 80 18-yr-old students learned a list of cities paired with their products. In experimental conditions, Ss were instructed in mnemonic usage to learn the city–product pairings. Control Ss were simply instructed to learn the pairings. Then all Ss were presented a list of Latin nouns and their translations to learn. Spontaneous transfer of the keyword strategy to the Latin task was observed only among 18-yr-olds. However, the 12-yr-olds could transfer the keyword strategy to the new task situation if they were told to "use a technique similar to the one used in the city–product task." Results are interpreted within a developmental elaboration theory framework. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attitude accessibility as a moderator of autonomic reactivity during decision making.

Attitude functionality was assessed in 2 experiments examining attitude accessibility as a moderator of physiological responses during decision making. In Study 1, experimental Ss but not controls rehearsed attitudes toward novel objects (abstract paintings). Subsequently, all Ss made rapid preference judgments for pairs of the paintings. In Study 2, attitudes were rehearsed by all Ss toward 1 of 2 mutually exclusive sets of abstract paintings. During the subsequent decision-making task, half the Ss made rapid pairwise preference judgments for rehearsed abstract paintings and half for pairs from the unrehearsed set. Autonomic measures were recorded continuously throughout both experiments. As predicted, in both experiments less autonomic reactivity was evident during the criterion pairwise preference task for groups for whom attitude rehearsal was relevant to the criterion task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Age differences in retention as a function of learning.

The hypothesis that observed age-related decrements in recall scores derive primarily from degree of acquisition rather than from retention deficits per se was investigated. 40 elderly and 30 young Ss learned 9 paired associates under equal learning opportunity, learning to criterion or overlearning conditions. Retention was measured at 20 min. and 1 wk. Elderly Ss learned less on equal exposure and required more trials to criterion, but once having learned the material retained it as well as young Ss. Trials beyond criterion did not enhance the retention scores of elderly Ss and may have introduced negative motivational factors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An empirical investigation of individual differences in time to learn.

Studied the magnitude and stability of individual differences in the amount of time required to achieve a criterion level of performance (time-to-criterion). Time-to-criterion was defined by (a) the amount of elapsed time and (b) the amount of on-task time required to attain the criterion. 90 8th graders were randomly assigned either to a mastery learning class in which all Ss were helped to attain an 85% mastery standard or to 1 of 2 nonmastery classes. Ss learned a 3-unit sequence of programmed material in matrix arithmetic. Results from the 82 Ss who completed the study indicate that time-to-criterion (defined in both manners) was an alterable human characteristic. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conformity behavior of schizophrenic subjects with maternal figures.

4 groups of 10 Ss each were used: (a) a group of Nondrug Poor Premorbid schizophrenic Ss, (b) a group of Drug Poors, (c) a group of hospitalized Alcoholics, and (d) a group of Normal control Ss. S was placed in a 2-choice situation, and asked to indicate his preference, over a number of trials, after having learned the preference of a cold, domineering, maternal figure. Conformity was measured in terms of 3 relatively independent response attributes. The results indicate that, as compared to the Nondrug schizophrenics: (a) the Drug schizophrenics manifested less conformity, (b) the Normals were uninfluenced, and (c) the Alcoholics tended to disagree with the negative mother. All groups were equally accurate in their perception of the 2 mothers. (24 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Initial preference of chicks from five rearing conditions for a hen or a rotating light.

Gave 239 NE51-strain 2-day-old domestic chicks a preference test between a nonbroody hen and a rotating light. The greatest preference for the hen was shown by Ss hatched and reared by a broody hen. Ss reared with a nonbroody hen and those reared socially in groups of 3 generally preferred the hen, but many made no choice and some preferred the light. Ss reared in isolation markedly preferred the light, and those previously exposed to the light spent virtually all of the time in its vicinity. The preference and the filial behavior exhibited by isolates support earlier work that chicks show no innate preference for the visual properties of the hen and suggest that the light is a stronger-than-normal imprinting stimulus. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Resumption of morphine self-administration by ex-addict rats: An attempt to modify tendencies to relapse.

Studied relapse tendencies in 69 morphine-dependent male hooded rats which had learned to drink bitter solutions of the drug in preference to water. Prolonged enforced abstinence (110 days) did not prevent Ss from resuming self-administration of morphine. Since the bitter taste of morphine may have become a secondary reinforcer, an attempt was made to extinguish responding for this source of reward. Abstinence was shortened to 12 days, during which Ss were given solutions of quinine to drink. On subsequent relapse tests these Ss consistently took less morphine than controls. Ss injected with methadone during the 1st 8 days of abstinence initially consumed slightly more morphine on relapse tests than did controls, but this difference was not maintained. (22 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of lesions of the gustatory neocortex on taste aversion learning in the rat.

In 5 experiments, 110 normal male Long-Evans hooded rats and 125 Ss with lesions of the gustatory neocortex (GN) were compared for their ability to learn aversions to taste cues paired with toxicosis. When the taste presentation was followed immediately by toxicosis, normal Ss and 8 Ss with lesions of the posterior (visual) neocortex learned aversions to sucrose, sodium chloride, quinine hydrochloride, and hydrochloric acid solutions. Ss with GN lesions learned aversions to all solutions except sucrose. In preference tests, all solutions were shown to be discriminable from water by both normal and GN-lesioned Ss. Under conditions in which a 6-hr delay separated taste presentation and toxicosis, normals again learned specific aversions to all 4 solutions, but Ss with GN lesions failed to learn specific aversions to sucrose, sodium chloride, and hydrochloric acid solutions. It was shown that the ability of Ss with GN lesions to learn aversions to sucrose and quinine depended on stimulus concentration. It is proposed that the data can be accounted for by postulating a change in the threshold for taste illness associations following GN lesions. (30 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Appetitive and aversive conditioning in thiamine-deficient rats.

Reports results of 3 experiments with albino male (n = 65) and female (n = 38) thiamine-deficient rats. 4 pairings of saccharin drinking with thiamine injection increased intake of saccharin whether tested before or after a further injection of thiamine. 2 injections of oxythiamine paired with saccharin drinking almost completely suppressed saccharin intake 1 wk. later, whether the diet during the week was thiamine enriched or thiamine free. Pairing thiamine injections with one flavor and oxythiamine injections with another in the same Ss produced a preference for the thiamine-paired flavor, but intake of both flavors was lowered in comparison with a control group. (21 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Social interaction modifies learned aversions, sodium appetite, and both palatability and handling-time induced dietary preference in rats (Rattus norvegicus).

Four studies examined whether socially transmitted diet preference could counteract the effects of a learned aversion, a palatability-based diet preference, a polyethylene glycol 20,000-induced sodium appetite, and a handling time-induced dietary preference. Results indicate that (a) Ss poisoned after eating a novel diet ate substantial amounts of the averted diet following interaction with conspecifics that had eaten the averted diet. (b) Following interaction with conspecifics that had eaten an unpalatable diet, Ss offered a choice between palatable and unpalatable diets ate more than twice as much unpalatable diet as did controls lacking social experience. (c) Sodium-deficient Ss offered a choice between sodium-enriched and sodium-adequate diets ate less than half as much sodium-enriched diet, following interaction with conspecifics that had eaten sodium-adequate diet as did controls lacking social experience. (d) Ss offered a choice between isocaloric, roughly equipalatable foods with long and short handling times chose the food having the longer handling time after interacting with conspecifics eating that food. It is suggested that social influence is a major factor in guiding diet selection by rats. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Further studies of the striate and extrastriate visual cortex in the tree shrew.

Trained 9 tree shrews (3 normal, 3 with striate cortex lesions, and 3 with temporal cortex lesions) to choose between 2 stimuli on the basis of orientation of stripes. The stimuli also differed in hue. When Ss reached criterion, hue became the relevant dimension, and shifts between orientation and hue continued. Normal Ss learned the original task and showed evidence of a learning set. Ss with temporal lesions were retarded in initial learning and reverted to chance level with each shift. Ss with striate lesions failed to master the initial problem. The temporal group was also impaired on daily intradimensional reversals. Results are interpreted as evidence for complementary functions of the 2 areas. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Changes in energy expenditure and work during response acquisition in rats.

The principle of least effort predicts that behavior will tend to maximum efficiency. To test this prediction, changes in the energy expended (VO?) and work performed per reinforcement were monitored continuously as rats learned to press a beam with a criterion force for liquid food rewards. All 12 Ss exhibited significant decreases in energy expended per reinforcement over the 16 days of observation. Of these, 10 Ss also decreased the work performed per reinforcement. Analyses of motor performance were undertaken to determine how motor programs for changing efficiency were generated. The 10 Ss showing decreased work reinforcement also exhibited significant decreases in the variability of temporal and kinetic response features and in mean response magnitude as a function of practice. Adjustments in work output were primarily accomplished by modifying temporal response features. The kinetic features remained relatively constant for these animals. The remaining 2 Ss differed in that response recruitment increased after Day 9. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Individual differences in learning: Visual versus auditory presentation.

Investigated the possible interaction of individual differences in learning with mode of presentation. Ss were college students; data analyses were replicated by conducting separate analyses for 2 groups of 77 and 83 Ss, respectively. Each S learned 4 test lists of 20 words each, 2 under auditory and 2 under visual presentation. The main analyses indicated that individual differences in learning were reliable and that individual differences were just as predictable across as within modalities. A complementary analysis showed that Ss could not be reliably classified in terms of auditory–visual preference scores. The findings give no support to the contention that Ss can be classified as auditory learners or visual learners. (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Voluntary control of human heart rate: Effect on reaction to aversive stimulation.

In anticipation of receiving painful stimuli, 20 female 21-27 yr old Ss learned to control their heart rate when provided with external feedback and reward for criterion heart rate changes and were instructed to increase or decrease their rate. Voluntary slowing of heart rate led to a relative reduction in the perceived aversiveness of the stimuli, particularly for those Ss who reported experiencing cardiac reactions to fear situations in daily life. It is concluded that biofeedback training for relevant physiological responses may possibly serve as a behavioral strategy for changing anxiety and fear reactions. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Failure of recovered lateral hypothalamic rats to learn specific food aversions.

Assigned 16 female Sprague-Dawley albino rats to either a group receiving lesions of the lateral hypothalamus, a group receiving lesions of the ventromedial nuclei of the hypothalamus, or a control group. After lesioned Ss recovered the ability to feed voluntarily, Ss were exposed to a procedure in which intake of a preferred diet was followed by LiCl poisoning. Whereas unoperated controls decreased subsequent intake of this diet and showed an aversion to it on a later preference test, most lesioned Ss showed little or no sign of having learned to avoid the poison-paired food. There was evidence, however, that the ability of brain-damaged Ss to learn this avoidance recovers over time. In Exp. II, intake of another preferred diet was accompanied by shock to the tongue. Again, lesioned Ss, unlike unoperated controls, appeared unable to associate ingestion of the diet with its aversive consequences. (35 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Acquisition of conditioned associations in Hermissenda: Additive effects of contiguity and the forward interstimulus interval.

Examined conditioned suppression of photokinesis (CSPK) by the marine mollusc in 3 experiments. In each experiment, groups of Ss received light (conditioned stimulus, CS) paired with high-speed orbital rotation (unconditioned stimulus, UCS), light and rotation explicitly unpaired, or no exposure to these stimuli. 24 hrs after training, all Ss were tested for CSPK in the presence of the light. 50 CS–UCS pairings resulted in a marginal CSPK, whereas 100 and 150 pairings produced strong CSPK. In Exp 2, delay between CS onset and UCS onset was varied between 1 and 10 s. The 10-s interstimulus interval (ISI) did not support conditioning, whereas 1-s and 2-s ISIs were effective. In Exp 3, CS–UCS pairings in which the CS preceded the onset of the UCS and ended with the offset of the UCS evoked stronger CSPK than either a CS that preceded the UCS and ended with its onset or a CS that was paired in simultaneous compound with the UCS. CS–UCS contiguity and the forward ISI act additively to establish the CS–UCS association. No differences were observed between groups that were untreated and that received the CS and UCS unpaired. Similarities are noted in the temporal characteristics of associative learning in these Ss and vertebrate species. (PsycINFO Database Record (c) 2010 APA, all rights reserved)