Ontogeny of passive avoidance learning in domestic chicks: Punishment of key-peck and running responses.

Determined the effect of the number of prepunishment acquisition trials on the age dependency of passive avoidance (PA) learning of the chick in keypeck and runway tests. In 9 experiments, 1- and 4-day-old Ss were first trained to respond for heat reward. After a variable number of reinforced acquisition trials (ATs), Ss' responses were punished with aversive wing shocks. Results show that the age dependency of PA learning of the young S is related specifically to the number of reinforced training trials given prior to PA testing. When several prepunishment ATs were given, 1-day-old Ss learned as quickly as 4-day-old Ss to withhold responding when punished. However, when only a few ATs preceded PA testing, 1-day-old Ss showed significantly less response suppression than 4-day-old Ss. Rather, results suggest that the 1-day-old chick, compared with the 4-day-old chick, is deficient in learning or detecting changes in stimulus– and/or response–reinforcement contingencies. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of apomorphine and haloperidol on response suppression learning of young chicks.

In four experiments, the effects of augmenting or blocking dopamine receptor activity on response suppression learning of Colburn?×?Colburn chicks were determined. In each experiment, 4-day-old chicks were trained to key peck for heat reward and then tested for response suppression learning by using either a response-contingent punishment or an extinction-punishment task. Before response suppression testing, different groups of chicks were injected ip with apomorphine (1.0, 2.0, or 4.0 mg/kg) either alone or after pretreatment with haloperidol (0.5 or 1.0 mg/kg). Regardless of the response suppression task used, chicks injected with apomorphine had difficulty inhibiting their responding; whereas, chicks injected with haloperidol, either alone or before apomorphine treatment, responded on fewer trials than saline-treated chicks. During extinction testing, 4-day-old chicks given only apomorphine showed the typical suppressive effect of punishment on responding rather than the paradoxical punishment-induced increase in responding found in normal 1-day-old chicks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Age-dependent improvement in passive avoidance learning of the young chick: Cholinergic mediation?

Studied cholinergic mediation of the age-dependent improvement in response suppression of the young chick by determining the performance of 144 Vantress?×?Arbor Acre 4-day-old chicks, pretreated with scopolamine (SCO), during passive avoidance (PA) and extinction testing. In Exp I, Ss were trained to keypeck for heat reward (prepunishment training), and then tested for PA learning under immediate, 2-sec-delayed, or no shock condition. Half of the Ss in each condition received saline injections before prepunishment training and .5 mg/kg SCO injections after training. The rest received .5 mg/kg SCO injections both before and after training. For Ss in both SCO groups, delaying shock onset resulted in significantly less response suppression than immediate response-contingent shock. In Exp II, 4-day-old Ss injected with saline or SCO were trained to keypeck for heat reward and then tested for resistance to extinction under response-contingent shock or nonshock conditions. Punishment decreased the number of extinction responses for both saline and SCO groups. Results indicte that the age-dependent improvement in response suppression of the young chick cannot be explained solely by a significant increase in central cholinergic functioning. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Form preferences in successive discrimination learning of young chicks.

In 4 experiments the effects of form and orientation pecking preferences of a total of 100 1- and 3-day old Vantress X Arbor Acre chicks on successive discrimination learning were determined using heat reinforcement. Results indicate that (a) the young chick has both circle and vertical orientation pecking preferences that are present during at least the 1st 3 days after hatching; (b) when either of these preferred cues is the nonreinforced cue, the young chick has difficulty in learning not to respond to it but learns quickly not to respond to an unpreferred cue; and (c) these pecking preferences can be modified by heat reinforcement, and the effects of this conditioning is evident in subsequent extinction and retention tests. It is concluded that form and orientation preferences, like brightness and color preferences, are important developmental constraints on conditioning of the young chick. (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

"Combined cue" test of conditioned inhibition in pigeons.

Conducted an experiment with 15 Silver King pigeons to determine whether the amount of positive-stimulus (S+) training affects the amount of response suppression induced by superimposing a novel stimulus on the S+ stimulus (external inhibition). An increase in the amount of training was accompanied by a reduction in the amount of external inhibition. The reduction in suppression could not be attributed to differences in response rate or to changes in stimulus control by S+. Results of the present study, taken together with those of a prior study, support the suggestion that the degree of external inhibition is codetermined by the degree of S+ stimulus control and by the strength of the behavior controlled by S+. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development of food recognition in young chicks: I. Maturation and nutrition.

Investigated age and food ingestion as factors influencing food recognition in 5 experiments with a total of 338 Burmese Red Junglefowl chicks. Newly hatched chicks pecked indiscriminately at sand and food; by 3 days of age, pecks were directed primarily at food. Pecking at food or sand had little effect on subsequent pecking at either stimulus until the chicks were 2-3 days old. Ingestion of food then served to facilitate pecking, but such facilitation did not occur until 10 min to 1 hr after ingestion. The effects that occurred on Day 3 were not specific to the stimulus pecked, but pecking at food and sand increased in frequency when the chicks had ingested food. Control experiments using a forced-feeding technique showed that these effects were due to ingestion of food and occurred only if food ingestion was associated with pecking. (16 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Simultaneous second-order conditioning produces S-S learning in conditioned suppression.

Explored simultaneous 2nd-order conditioning of one stimulus (S2) by another (S1) in a conditioned suppression preparation. In Exps I (40 female Holtzman rats) and II (32 male Holtzman rats) 2nd-order conditioning of S2 was attenuated by subsequent extinction of S1. Sequential presentation of the same stimuli produced similar levels of conditioning of S2 that were not affected by extinction of S1, results that replicate previous findings (R. A. Rescorla, 1980). Exps III (32 females) and IV (32 males) found that sensitivity of a simultaneous S2 to changes in S1 depended on S1 receiving few separate reinforced or nonreinforced presentations prior to 2nd-order conditioning. Circumstances are suggested under which the typical stimulus–response learning observed in 2nd-order conditioned suppression can be converted into stimulus–stimulus learning. (13 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Behavioral and computational models of spatial attention.

Pigeons pecked for food in a spatially cued choice reaction time (RT) task. A brief (50-msec) white light appeared on a left or right key and probabilistically predicted the location (on either the left or right key) of a subsequent target stimulus. The time between cue and target onset (stimulus onset asynchrony), the base rate of left cues, and the probability that the cue correctly predicted the target (cue validity) were experimentally varied. The mean RT to respond to the target key was faster on correctly cued trials (defining a validity effect), decreased for both valid and invalid trials as stimulus onset asynchrony increased (defining an alerting effect), showed a variety of base-rate effects, and did not depend on cue validity. It is shown with a computational-processing model that dynamic interactions of short-term and associative memory processes are sufficient to produce these attention-like empirical phenomena. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A Simon Effect in Pigeons.

Pigeons pecked left versus right keys contingent upon the color presented at 1 of those locations. Spatial-response latencies were shorter when the color appeared at the same location as the required response than at the opposite location. This Simon effect occurred when the stimulus on the alternative key was constant, varied from trial to trial, or changed when the color cue appeared and when the reinforcement probability for correct responses was the same on corresponding as on noncorresponding trials. Humans performing the same task by touching the keys also showed the Simon effect. These findings demonstrate that for pigeons, too, a relevant symbolic cue activates a spatial code that produces faster responses at the location corresponding with the activated code. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An inhibitory within-compound association attenuates overshadowing.

According to the comparator hypothesis (Miller & Matzel, 1988), cue competition depends on the association between a target stimulus (X) and a competing cue (e.g., an overshadowing cue [A]). Thus, it was expected that overshadowing would be reduced by establishing an inhibitory-like relationship between X and A before compound conditioning. In three lever press suppression experiments with rats, this expectation was supported. Experiment 1 showed that establishing an inhibitory X-A relationship reduced overshadowing. In Experiment 2, degrading the inhibitory-like relationship before conditioning allowed reinforced AX compound trials to result in overshadowing. Experiment 3 replicated the results of Experiment 2 when the inhibitory relationship was degraded after compound conditioning. The results support the view that within-compound associations are necessary not only for retrospective revaluation, but also for conventional cue competition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Further studies of hippocampal representation during odor discrimination learning.

The contribution of hippocampal and nonhippocampal memory processing to simultaneous-cue odor discrimination learning was assessed. In this task rats with hippocampal system damage consequent to fornix lesions (fornix rats) were severely and persistently impaired in discrimination learning, acquisition of learning set, and concurrent discrimination, although they occasionally solved some problems at a normal rate. By using those problems on which fornix rats succeeded, to permit comparisons of performance strategies with normal rats, differences between groups were shown on response latency measures and on probe trials involving the novel pairing of familiar odors. Normal rats had a bimodal distribution of response latencies, and their latency depended on where the S+ was presented. Fornix rats had short response latencies and responded equally quickly wherever the S+ was presented. Furthermore, when the representation of familiar S+ and S– odor pairs was challenged in probe trials, normal rats responded appropriately to the correct stimulus, whereas fornix rats behaved as if presented with a new odor pair. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Taste-mediated conditioned aversion to an exteroceptive stimulus following LiCl poisoning.

Describes 2 experiments with a total of 54 female hooded rats. When a light was paired with a novel taste in a barpressing situation and this pairing was followed by toxicosis, the light subsequently suppressed extinction responding. Conditioned suppression did not occur if the light-toxicosis pairing was unaccompanied by the distinctive taste cue. Additionally, no suppression was obtained if the light-taste association was first formed with a palatable stimulus which was subsequently made aversive by pairing with toxicosis outside the test situation. Results are interpreted in terms of (a) a distinction between the cue and reinforcing properties of the taste or (b) the necessity for a degree of temporal contiguity between the exteroceptive stimulus and the effects of toxicosis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Increased priming interference at a long SOA with brief masked targets.

Tests prediction of a model of priming proposed by B. E. McLeod and R. E. Walley (1989) in which interference (ITF) is caused by inhibitory processes between nodes in semantic memory. This model predicts that ITF normally found in a high cue validity condition at long stimulus onset asynchrony (SOA) will be considerably increased when a brief target is masked. 80 male and female, native English-speaking Ss participated; within S variables were prime type, prime relatedness, and target condition. 192 trials were given in 2 blocks of 96 trials; 25% were nonword trials. The task was a primed lexical decision with an SOA of 800 ms. Cue validity was high or low; targets were brief, masked in either block 1 or block 2 of trials. In the high cue validity condition, both reaction time (RT) and error data show increased ITF when the brief target was masked. Results confirm that target node activation is considerably reduced. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Learning of absolute and relative distance and direction from discrete visual landmarks by pigeons (Columba livia).

In an open-field search task, pigeons (Columba livia) were trained to search for a goal located at the midpoint of the hypothetical line connecting two discrete visual landmarks positioned 60 cm apart. In Experiment 1, global orienting cues were absent. After reaching training criteria, pigeons were tested with novel interlandmark distances. Search location and error on test trials suggested pigeons learned relative distance. In Experiment 2, a global orienting cue was present. After reaching training criteria, pigeons were again tested with novel interlandmark distances. Results suggested pigeons learned relative and absolute distances. In Experiment 3, pigeons searched at the midpoint of rotated arrays in both the presence and absence of an orienting cue indicating learning of relative direction. In Experiment 4, pigeons searched in the appropriate goal direction when presented with a single landmark in the presence of the orienting cue but not in its absence indicating learning of absolute direction. Results implicate a stable frame of reference as critical to spatial coding strategies and suggest pigeons are able to code location based on absolute and relative distance and direction from discrete visual landmarks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of punishing active avoidance in young and adult rats.

Examined whether age-related differences in suppression occur when a learned response is punished. 8 groups of weanling and adult male Holtzman rats (N = 96) received active-avoidance training and subsequent punishment for that response. Following active avoidance, Ss were assigned to a regular extinction group or to 1 of 3 punishment-delay (0-, 2-, or 10-sec.) groups, which received shock in the goal box. Although weanlings and adults were equivalent in active-avoidance acquisition, under the immediate punishment condition immature Ss required significantly more trials to learn passive avoidance. A delay-of-punishment gradient was obtained in adults but not in weanlings. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Administration of dexamethasone prior to training blocks ACTH-induced recovery of an extinguished avoidance response.

Pretest administration of adrenocorticotropic hormone (ACTH) has been shown to produce recovery of an extinguished avoidance response, presumably because endogenous ACTH is a component of the original training memory. However, another possible explanation of this finding is that administration of the peptide acts as a novel stimulus that "disinhibits" the extinguished response. To test this disinhibitory hypothesis of ACTH-induced recovery of an extinguished avoidance response, 49 male rats received subcutaneous injections of dexamethasone (.4 mg/kg) or saline 2 hrs prior to training and extinction. ACTH should not be a component of the training memory in Ss given dexamethasone (which blocks endogenous release of ACTH) but would be a relatively novel stimulus condition at testing. Pretest administration of ACTH was effective in alleviating performance deficits induced by extinction only for Ss given saline prior to training and extinction. ACTH had no effect on the avoidance responding of Ss given dexamethasone. Findings suggest that pretest administration of ACTH affects retrieval processes rather than acts as a disinhibitor. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Experimental study of unconscious influences: Ultrasound as a stimulus.

Used ultrasound as a stimulus to study its effects on behavior without S awareness. In Exp I evoked responses were elicited in 7 of 24 undergraduates by ultrasonic tones when Ss were reporting the presence of no stimulus. In Exp II with 20 male Ss, galvanic skin response conditioning to a compound stimulus made up of ultrasound and a red light resulted in shorter latencies to the compound stimulus than to the red light alone, during extinction. The differences did not appear among control Ss, supporting the occurrence of conditioning without awareness. In Exp III with 16 Ss, reaction-time performance was disrupted by providing ultrasound as an anticipatory cue for 1 of 2 lights over 150 trials and then reversing the ultrasound-light pairing. The ultrasound did not facilitate reaction time to the paired light during the 1st 150 trials, however. Results support learning without awareness, and the method is discussed as it might be extended to the study of unconscious influences and to clinical applications. (75 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Second-order excitation mediated by a backward conditioned inhibitor.

Conditioned suppression studies with rats explored the informational content of a backward conditioned inhibitor. Pairings of an unconditioned stimulus/stimuli (UCS) and Stimulus 1 (US > S1) established S1 as an inhibitor in Exp 1. Pairing the inhibitor S1 with a novel S2 (S2→S1) promoted excitatory second-order conditioning (SOC) to S2, which suggested S1 was well associated with the UCS. Degrading presumed S1-US associations in Exp 2 by S1- (extinction) treatment eliminated S2's excitation while preserving Sl's inhibition. Exp 3 and 4 converged in showing that S2 was not an excitor when Pavlovian conditioned inhibition (CI) was the inhibitory treatment prior to the SOC phase, but instead acted as a second-order inhibitor. Results are discussed in relation to the temporal coding hypothesis, the SOP ("sometimes opponent process") and Rescorla-Wagner models of conditioning, and the associative structure of SOC. Also, the data suggest that backward inhibition is special and that not all forms of CI are equal. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of ageing on visual discrimination learning in Drosophila melanogaster

Two experiments examined conditioned suppression of the Proboscis Extension Response (PER), unconditionally released by sucrose stimulation of gustatory tarsal receptors, in young (7-day-old), middle-aged (30-day-old) and old (50-day-old) Drosophila melanogaster males, reared at 25 degrees C. Individual flies were trained in a differential conditioning procedure in which a white stimulus signalled a quinine reinforcer, whereas a black stimulus was non-reinforced. When trained from the outset with the discriminative procedure, flies of all ages acquired the discrimination, although the acquisition of PER suppression to the white stimulus was retarded in middle-aged and old flies. The retardation of the acquisition of PER suppression in middle-aged and old flies was replicated in a second study in which the files received simple conditioning to the white stimulus prior to discrimination training.     

Degraded contingency revisited: Posttraining extinction of a cover stimulus attenuates a target cue's behavioral control.

In a Pavlovian conditioning situation, unsignaled outcome presentations interspersed among cue-outcome pairings attenuate conditioned responding to the cue (i.e., the degraded contingency effect). However, if a nontarget cue signals these added outcomes, responding to the target cue is partially restored (i.e., the cover stimulus effect). In 2 conditioned suppression experiments using rats, the effect of posttraining extinction of the cover stimulus was examined. Experiment 1 found that this treatment yielded reduced responding to the target cue. Experiment 2 replicated this finding, while demonstrating that this basic effect was not due to acquired equivalence between the target cue and the cover stimulus. These results are consistent with the extended comparator hypothesis interpretation of the degraded contingency and cover stimulus effects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)