Eating in the pigeon (Columba livia): Movement patterns, stereotypy, and stimulus control.

Used high-speed cinematography to analyze the eating behavior of 32 pigeons and to clarify the nature of its control by stimulus and motivational variables. Eating-response sequences may be functionally subdivided into a series of individual movement patterns whose duration and sequential organization exhibit a range of stereotypy comparable with that of movement patterns with an obvious communication function. Food deprivation did not affect the topography or spatiotemporal organization of the eating-response sequence but increased the rate at which such sequences are emitted. Stimuli coming from food elicit and orient many components of the eating response and serve as coordinating links in the causal chain that integrates individual movement patterns into an adaptive behavior for the efficient ingestion of food. (36 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The acquisition of stimulus control over released pecking by hatchling chicks (Gallus gallus).

Analyzed the spatial and dynamic stimulus characteristics of the pecking arrow display that control simple release and/or learned release of pecking by 254 hatchling chicks in 5 experiments. Findings show (1) a pronounced preference by Ss to peck at red rather than green illuminated lamps, (2) significantly greater pecking by Ss to lamps attached to, and on the floor beneath, the pecking arrow during the display, and (3) little evidence that placement of a stimulus on the arrow, on the floor beneath the arrow, or in both locations differentially affected frequency of pecking to matching stimulus colors. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Response strength as a function of stimulus novelty: Concept formation in the pigeon.

Cites a previous study which showed that a distinctive CS presented on the 1st trial of acquisition generated more responses after extinction than another CS presented regularly during acquisition. In the present study 140 pigeons were presented with a different distinctive CS on each 1st trial of 5 acquisition sessions. Ss were then broken down into 7 groups which were tested, following extinction, for residual response strength of (a) Day 1 novel CS, (b) Day 2 novel CS, (c) Day 3 novel CS, (d) Day 4 novel CS, (e) Day 5 novel CS, (f) the regular CS, and (g) a novel CS never presented before. Contrary to the previous study where a novel CS inhibited responding, Group 7 exhibited the most responding in this study. Results support a concept formation interpretation of the previous study and are difficult to explain from a "stimulus trace" or "identical elements" position. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the benefit of dimensional comparisons.

People not only use social comparisons to evaluate their abilities, they also engage in dimensional comparisons, comparing their own achievement in different domains. Processes of dimensional comparison have contrasting effects on subject-specific self-concepts: downward dimensional comparisons result in higher self-concept in the intraindividually better domain, whereas upward dimensional comparisons result in lower self-concept in the intraindividually weaker domain. Two field studies and 1 experimental study were conducted to investigate whether the effects of downward or upward dimensional comparisons are stronger. In Study 1 (N = 319), downward dimensional comparisons proved to be stronger than upward dimensional comparisons. In Study 2 (N = 1349), the same pattern was found with reading test scores as well as grades as achievement indicators. In Study 3 (N = 81), the authors found larger effects for downward than for upward comparisons in both self-perceived competence and satisfaction with test outcomes in an experimental setting. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pro-Leu-Gly-NH? serves as a conditioned stimulus in the acquisition of conditioned tolerance.

The effect of Pro-Leu-Gly-NH? (MIF) on the acquisition of tolerance to morphine-induced antinociception and its efficacy as a cue predictive of morphine administration was examined. Daily administration of MIF prior to morphine injection did not attenuate the acquisition of tolerance to the antinociceptive properties of morphine, as measured by the latency to hindpaw lick in a hot-plate test of analgesia. When the animals were tested 72 hrs later without MIF pretreatment, they appeared to lose tolerance, as indicated by longer latencies to paw lick. These data suggest that in some situations MIF may interfere with the acquisition of tolerance by acting as a cue that reliably predicts the antinociceptive properties of morphine. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Analysis of stimulus control treatment of sleep-onset insomnia.

Examined the components responsible for the efficacy of the stimulus control treatment of sleep-onset insomnia. 47 college students with sleep-onset insomnia were assigned to 1 of 5 treatment conditions (stimulus control, noncontingent control, countercontrol, temporal control, and waiting list). Ss were instructed not to expect improvement until after the 4th treatment session. Only stimulus control and a treatment violating the associative aspects of stimulus control produced significantly greater improvement in reported latency to sleep onset than the waiting-list condition. Results are discussed in terms of several possible explanations for improvement due to so-called stimulus control treatment for insomnia. (10 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Overshadowing effects in the stimulus control of morphine analgesic tolerance.

Attempted to replicate previous demonstrations of classical conditioning of morphine analgesic tolerance and to determine whether stimulus overshadowing effects might explain previous conflicting findings. In Exp I, 8 groups of male Sprague-Dawley rats received a series of 10 morphine (5 mg/kg) and/or saline injections, differing only with respect to the contingency between a compound visual-auditory CS and the substance injected. When tested for analgesic responding to morphine in the presence of the compound CS, only those groups for which the CS and morphine injections were paired during the acquisition sequence evidenced tolerance. In Exp II, tolerant Ss were tested in the presence of 1 component of the compound CS. When a loud tone (85 db) was used in the compound, less analgesic tolerance was elicited later by the weaker visual stimulus alone. This differential stimulus control of the analgesic response suggests that overshadowing may contribute to failures to replicate conditioned morphine tolerance. It is possible that internal morphine-produced stimuli may overshadow external cues. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Measurement of stimulus control during discriminative operant conditioning.

Procedures in common use in discriminative operant conditioning are examined. It is concluded that they do not provide useful measures of stimulus control during acquisition because they confound the discriminative stimuli with antecedent reinforcement-nonreinforcement. Procedures which avoid confounding and provide measures of stimulus control during an uninterrupted acquisition process are described. 1 such procedure is applied in an experiment on sequential effects in discrimination learning. Substantial effects of antecedent reinforcement-nonreinforcement on generalized response probability and on the difference in probability of response to the discriminative stimuli are shown. The existence of effects of this type indicates that confounding can introduce serious biases into the measures of stimulus control in discriminative operant conditioning. (19 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the selective effects of a patterned masking stimulus.

Investigated previous findings which suggest that a patterned masking stimulus, presented immediately following tachistoscopic presentation of letter rows, produces large decrements in the recall of letters from the central positions in the rows but has little effect on recall from either end of the displays. 4 experiments with 92 undergraduate Ss confirm the existence of a selective masking effect. The effect was obtained following exposure durations which varied from 30-200 msec. and with both full- and partial-report techniques. Also the selective masking effect was limited to multiletter displays in that it was shown that single letters were masked equally well across the positions used for an entire row. Results suggest that both ends of multiletter displays are processed and identified before the center positions of the displays are processed. (French summary) (15 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of conditioned stimulus intensity on visually conditioned heart rate change in the pigeon: A sensitization mechanism.

In visually conditioned heart-rate change in 30 White Carneaux pigeons, increasing the conditioned stimulus intensity enhanced performance. The effect, which only appeared at high intensity levels, was obtained during acquisition and with rigorous maintenance of constant stimulus conditions. A similar effect was obtained with 10 sensitization control Ss. Evidence is presented that the stimulus intensity effect during conditioning may have totally reflected increased sensitization such that the locus of the effect was upon performance rather than conditioning per se. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Exposure to the unconditioned stimulus alone: Effects on retention and acquisition of conditioned suppression.

In 3 experiments with 104 male Sprague-Dawley rats, repeated exposure to an electric-shock UCS resulted in a decrement in retention of conditioned suppression evoked by a previously established excitatory CS and retarded subsequent acquisition of conditioned suppression to a novel CS paired with shock. Exp I showed that 10 sessions of exposure to shock alone were required to produce a decrement in retention of conditioned suppression, whereas retardation in the acquisition of conditioned suppression was obtained following either 5 or 10 sessions of exposure to shock alone. Exp II demonstrated that both of these effects were directly related to the intensity of the shocks. In Exp III, the decrement in retention of conditioned suppression produced by 10 sessions of exposure to shock alone was inversely related to the interval between the last exposure to shock and the test of the target CS. Findings are discussed in terms of associative and nonassociative accounts of the effects of UCS-alone procedures. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Separation of drug effects on timing and behavioral inhibition by increased stimulus control.

Impulsive behavior may represent, in part, a failure of behavioral inhibition (the ability to delay or inhibit a response). In this study, use of a multiple signaled–unsignaled differential-reinforcement-of-low-rates (DRL) 15-s schedule allowed examination of drug effects in conditions in which level of stimulus control differed. Results showed that whereas diazepam increased premature responding during signaled and unsignaled DRL components, amphetamine and Δ?-tetrahydrocannabinol increased premature responding primarily during unsignaled components when timing was necessary for efficient performance on the task. In contrast, primozide and desipramine increased long-delay responses across both components, resulting in longer mean interresponse times. Collectively, these results suggest that the use of different levels of stimulus control may aid in separation of drug effects on timing and other behavioral processes, including behavioral inhibition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Contextual stimulus control over operant responding in pigeons.

Gave pigeons (N = 48) 17 days of single stimulus (S) training with a house light and tone context. Ss were then given 20 days of discrimination training with a 555-nm green response key (S+) and a line (S-). For Group 1 the light and tone were paired with S+ (S+/context), for Group 2 they were paired with S- (S-/context), and for Group 3 they were paired with both (no context change, or NCC). For each group a matched control group experienced the same stimulus configurations without the prior single stimulus training. Then all groups were tested for wavelength generalization. Of the 3 experimental groups, the S+/context group acquired the discrimination the fastest, the S-/context group started poorly but eventually mastered the discrimination, and the NCC group never mastered it. The experimental groups yielded flatter wavelength gradients than did their matched controls, which suggests blocking by the contextual stimuli. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stimulus information and primate discrimination learning: Utilization of preresponse stimulus information following acquisition.

Notes previous research which indicates that the subhuman primate, during acquisition of a simultaneous 2-choice pattern discrimination, bases its choice on information obtained when the discriminative cues are 1st observed. Results of an experiment with 5 wild-born rhesus monkeys indicate that the monkey's propensity to utilize initially sampled discriminative information is not peculiar to acquisition but is also a dominant factor during performance of mastered discriminative tasks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The peripheral unconditioned stimulus pathway in a model learning system involving defensively conditioned heart rate change in the pigeon.

Conducted 3 studies using White Carneaux pigeons. The peripheral pathway transmitting the UCS information is described in a vertebrate model system for studying learning-visually conditioned heart rate change in the pigeon. In this system footshock serves as the UCS, and it is shown that the effective stimulation field of this stimulus, defined with respect to the unconditioned cardioacceleratory response, includes cutaneous dermatomes 21-25 (L1-Sl). The stimulus information is then transmitted by Group III and IV fibers in portions of the femoral and sciatic nerves which enter the spinal cord over segments 21-25. Further, it is shown that interrupting this pathway by section of dorsal roots 21-25 precludes establishing conditioned heart rate change with footshock as the UCS. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dissociation of stimulus compounds by pigeons.

Used a matching-to-sample (MTS) procedure to investigate short-term memory for compound visual stimuli in 10 mixed-breed pigeons. In Exp I, a symbolic MTS procedure was used. Three Ss were trained to match element samples, and 3 were trained to match compound samples. Findings indicate that the compound-trained group did not learn to match the compound samples in terms of element matching rules but rather processed them as unitary events. In Exp II, Ss were trained to match either element or compound samples in a true MTS task. Both groups were able to match elements and compounds in the transfer test. Findings show that at least some compound stimuli were represented in a unitary, nonanalytic fashion until the S was exposed to the elements of the compound in isolation from the compound. (36 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the acquisition of new declarative knowledge in amnesia.

In 2 experiments, the acquisition of new declarative knowledge was examined in amnesic patients and in 7 groups of controls, with a study-only procedure that delayed testing until the conclusion of training. The study-only procedure was compared with a standard procedure in which study and test trials alternated (study-test). The amnesic patients acquired new factual (declarative) knowledge at an abnormally slow rate, learning more with the study-only procedure than with the study-test procedure. Controls exhibited the opposite pattern. The advantage of the study-only procedure for amnesic patients was related to the presence of frontal lobe dysfunction. The 2 groups exhibited a similar ability to use their knowledge flexibly, suggesting that the information acquired by amnesic patients was based on their residual capacity for declarative memory. In addition, the capacity for factual learning in amnesia was proportional to the capacity to recollect specific events in the learning session. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Categorical scaling of stimulus duration by humans.

Normal human adults performed on an analogue of the categorical timing procedure, used by J. G. Fetterman and P. P. Killeen (1995) with pigeons, by classifying a set of 18 or 24 tone durations in 3 or 4 categories. Use of the different categories was an orderly function of stimulus duration in all cases, and data showed a close approximation to superposition, indicating conformity to scalar timing. Both these results were similar to data from pigeons. A model using memory representations of the category-range geometric means with scalar variance fitted data well in nearly all respects. The results emphasize human and animal similarities in categorical timing and conformity of human behavior to scalar timing principles. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the control of attention.

An early interest in cognitive processes led me to study with Mike Posner from whom I acquired the intellectual tools to follow Hebb’s (1949) advice that “Everyone knows that attention and set exist so we had better get the skeleton out of the closet and see what can be done with it.” Using variants of the model task Posner developed for exploring the control of visual attention we have demonstrated that endogenous shifts of attention are not generated by unexecuted oculomotor activation, that endogenous and exogenous shifts of attention are fundamentally different on a variety of dimensions and that an aftermath of exogenous (but not endogenous) orienting, inhibition of return, facilitates search by encouraging orienting to novel items. A research strategy for understanding ambiguous forms of orienting (e.g., that controlled by conspecific gaze) is proposed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Behavioral control, aversive stimulus frequency, and pituitary-adrenal response.

Six female Long-Evans rats were trained to leverpress under a free-operant shock postponement schedule, and each S was linked to a control that received shock whenever the S did to test the hypothesis that the pattern of corticosteroid response would be affected by both the frequency of shock received and the availability of behavioral control. The shock postponement interval (R-S) was varied (5, 10, 20, 40, or 80 sec) over blocks of sessions. Corticosteroid levels were taken prior to training and before and after selected sessions. Results show that frequency of shock had no major impact on physiological processes controlling the corticosteroid response; however, when Ss had the opportunity to control aversive events, a change in corticosteroid response was evident relative to controls. The rates of responding and of shock were inversely related to the R-S interval. Corticosteroid levels were unrelated to the R-S parameter. Corticosteroid levels of Ss were significantly higher than basal levels at the beginning of a session; by the end of a session, these levels were significantly reduced, although still above basal levels. These results were reversed for controls. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)