Heart rate conditioning with pentobarbital as a conditioned stimulus and amphetamine as an unconditioned stimulus.

Injected pentobarbital (PB) into rats 20 min after they were placed in an apparatus where heart rates were recorded. Amphetamine was injected after they were removed from the apparatus 29–30 min later. A Pavlovian conditioned response (CR) began after 3 or 4 trials in the form of a failure of conditioned Ss to show the same decline in heart rate obtained in controls after the PB injection. On later trials, the amphetamine was not injected until 50 min after the PB, and the CR was most obvious during the period 30–50 min after the PB injection. The pharmacological effects of PB were necessary for conditioning because the CR was not obtained (a) when normal saline was substituted for the PB after successful conditioning or (b) when saline was used instead of PB throughout. Because of the speed and effectiveness of the conditioning, we believe the mechanism responsible for it has homeostatic regulation as its natural role. It was puzzling that environmental cues seemed to have a role in the conditioned stimulus complex, because conditioning was not apparent when the drug–drug pairings were administered in the home cage. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Experimental analysis of a film used as a threatening stimulus.

In an effort to identify sources of stress reaction, a threatening film depicting a primitive genital operation was analyzed experimentally by dividing it into 3 sections of different contents. Impact of the sections was compared on physiological and psychological measures of stress reaction. The threat value of the film depended not only on the genital operation scenes, interpreted by previous investigators as producing castration anxiety, but also upon other types of contents, such as nudity. Moreover, in addition to differing in degree of disturbance produced, the film sections resulted in variation in the pattern of affects. Such patterns cannot be studied at the physiological level of analysis. Personality factors also determined reactions to the film threats. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Psychology as an ambiguous attitude stimulus.

College freshmen and their parents applied each of 3 methods for assessing public image (a naturalistic approach, a listing of adjectives, and a Likert scale) to 6 professions. A rank ordering was obtained and ranks were compared across methods. (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)     

Rabbit eyelid conditioning as a function of unconditioned stimulus duration.

Reports eyelid conditioning data for 85 male New Zealand white rabbits, employing UCS durations of 50, 100, and 200 msec. Ss with a 50-sec UCS were slower to start conditioning than the 100- or 200-msec groups. The 200-msec group reached a lower terminal performance level than the other 2 groups. Results are related to drive-reduction theory and to possible technical difficulties in the presentation of the cheek-shock UCS. (17 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Angiotensin III-induced dipsogenic and pressor responses in rodents.

Three experiments examined responses to angiotensins in 64 male Sprague-Dawley rats, 64 male Mongolian gerbils, and 40 Octodon degus—a South American rodent. In Exp I, injections of [des-Asp–1]-angiotensin I ([des-Asp–1]-AI), angiotensin II (AII), and angiotensin III (AIII), at doses of .001–2 mg/kg (sc), induced drinking in the rat and degus, but not in the gerbil. In Exp II, pretreatment with captopril (50 mg/kg), an angiotensin converting enzyme inhibitor, prevented the endogenous conversion of sc injected [des-Asp–1]-AI to AIII and prevented drinking in rats and degus. The pharmacological artifact of hypovolemia caused by angiotensin-induced increases in vascular permeability was not observed in members of these species. In Exp III, blood pressure changes resulting from injections of AII and AIII in rats and gerbils were measured. Significant pressor elevations were seen following the administration of both analogs, although AII was more potent. Results demonstrate that AIII is dipsogenic in rats and degus and serves as a pressor agent in rats and gerbils. No explanation was found for the gerbil's relative lack of dipsogenicity to the presently tested angiotensins. (54 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reaction time as a function of manifest anxiety and stimulus intensity.

"The present study was designed to investigate the relative increase in drive of anxious and nonanxious individuals as a function of different intensities of stimulation… The results indicated that both an increase in manifest anxiety and an increase in stimulus intensity were effective in increasing the speed of reaction during training, and in raising the height of the temporal gradient of response strength; neither factor was effective in steepening the slope of the gradient." 17 references. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Extreme response tendency as a function of emotional adjustment and stimulus ambiguity.

Explored relationships between the tendency to check extreme categories on the semantic differential, emotional adjustment, and ambiguity of stimuli to be rated. 115 undergraduates were administered the Welsh A and R scales of the MMPI and asked to rate 9 stimuli on 21 semantic differential scales. Stimuli were chosen to reflect 3 levels of ambiguity (verbal concepts, TAT pictures, and Rorschach inkblots). 3 groups of 10 Ss each were formed representing high and low combinations of the A and R scales. Results suggest that anxiety (high A, low R) is related to extreme response tendencies and repression (low A, high R) is related to use of the neutral category. "Adjusted" Ss (low A, low R) tend to make more use of the intermediate categories. The relative tendency of high-A Ss to make extreme responses was most pronounced when stimuli were most ambiguous. Discussion focused on the relationships between scale-checking behavior, "psychopathology," and meaningfulness of material to be rated. (15 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differences in gradients of stimulus generalization as a function of psychiatric disorder.

On the basis of the "Dollard and Miller… principle that 'increasing the strength of the drive raises the entire gradient of generalization… ' [and that]… such emotional states as fear, anxiety, and guilt can acquire the properties of a drive… . The present research investigates the hypotheses that there are differences in the shape of the SG gradients among psychotic, neurotic, and control Ss… . The results indicate that (a) the psychotics showed more generalization than the nonpsychotics; (b) the neurotics showed less… than the psychotics, but did not differ from the controls; and (c) the brain-damaged Ss showed more generalization than the nonpsychotics, but they did not differ from the psychotics." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stimulus generalization as a function of stimulus novelty and familiarity in rats.

Three experiments used rats as subjects to investigate the generalization of conditioned responding between stimuli as a function of the subjects' exposure to these cues prior to conditioning. Experiment 1 used a between-subjects design, food as the reinforcer, and measured the tendency of subjects to approach the site of food delivery during the stimuli. Generalization of this response was more marked when the training and test stimuli were equated in terms of their novelty (i.e., when both were novel or both were familiar) than when the stimuli differed in this respect (i.e., when one was novel and the other was familiar). Experiments 2a and 2b used within-subjects designs to confirm the reliability of the results of Experiment 1. Implications of these results for current theories of stimulus representation are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Angiotensin's contribution to dipsogenic additivity in several rodent species.

Significant positive correlations were obtained between plasma angiotensin levels and drinking following the administration of polyethylene glycol (PEG) in rats, gerbils, and hamsters and following isoproterenol (ISOP) in rats and gerbils, but not in a South American rodent, Octodon degus (degus). Hamsters revealed elevations in plasma angiotensin following ISOP but no drinking, whereas degus failed to show changes in plasma angiotensin to either treatment, although drinking occurred following PEG. A second experiment indicated that gerbils and degus possess circumventricular organ (CVO) angiotensin III receptors. In a final experiment, rats and gerbils revealed dipsogenic additivity when challenged with either PEG or ISOP paired with 2.5 M NaCl. Degus and hamsters indicated additivity only with PEG and 2.5 M NaCl combined. Despite the presence of CVO angiotensin receptors in degus and hamsters, it is concluded that the important component of the hypovolemic dipsogenic stimulus in members of these species may be activation of volume receptors rather than brain angiotensin receptors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Speed of form recognition as a function of stimulus factors and test anxiety.

This study evaluated the usefulness of several theories about Rorschach color shock. Using an arabic-greco-latin square design, the influence of color, pattern of color, figure, and anxiety level on response time was investigated in 192 Ss. "The influence on response time of stimulus attributes affecting complexity was confirmed. The hypotheses that highly anxious persons are greatly affected by colors are not confirmed. Partially verified were predictions made from Hullian behavior theory. It was found that drive level and figure difficulty were related to response time in that highly anxious persons became slower with increasing difficulty of figure during warm-up trials. During the test series, however, the predicted relationship was not found." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stimulus–response compatibility as a function of stimulus code and response modality.

The concept of stimulus-response compatibility can be differentiated into set-level and element-level compatibility. The relation between these 2 types of compatibility was examined by varying stimulus code (spatial or verbal) and response modality (manual or vocal) in 2-choice tasks that used left-right stimuli and left-right responses. Element-level compatibility was an increasing function of set-level compatibility and larger for verbal than for spatial stimuli. The positive relation between set- and element-level compatibility was due to differences for the congruent mapping but not the incongruent mapping. The results can be characterized in terms of (a) a continuum along which the relative compatibility of the responses with spatial and verbal stimuli varies and (b) a dual-route conception of response selection in which a direct, or automatic, route is involved only when a congruent mapping is in effect. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Nicotine as a conditioned stimulus: Impact of attention-deficit/hyperactivity disorder medications.

People diagnosed with attention-deficit/hyperactivity disorder (ADHD) are at an increased risk to start smoking and have greater difficulty quitting. Nicotine, one of the principal addictive components of tobacco smoke, functioned as a conditioned stimulus (CS) for intermittent sucrose delivery in a Pavlovian drug discrimination task with rats. This study compared the ability of commonly prescribed ADHD medications (i.e., methylphenidate, atomoxetine, and bupropion) and additional dopamine reuptake inhibitors (i.e., cocaine and GBR 12909) to substitute for the CS effects of nicotine. Atomoxetine was also used to antagonize these CS effects. Rats acquired the discrimination as evidenced by increased dipper entries in nicotine (0.2 mg base/kg) sessions as compared with saline sessions. Nicotine generalization was dose dependent. Bupropion (10 and 20 mg/kg), methylphenidate (10 mg/kg), and cocaine (5 and 10 mg/kg) partially substituted for the 0.2 mg/kg nicotine CS. Atomoxetine did not substitute for the nicotine CS; however, atomoxetine (1 to 10 mg/kg) partially blocked nicotine's CS effects. These results suggest that atomoxetine, bupropion, and/or methylphenidate may be effective treatments for people diagnosed with ADHD and addicted to nicotine. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reaction time and response amplitude as a function of anxiety and stimulus intensity.

"The present study was concerned with reaction time and response amplitude as a function of C S intensity and anxiety (Taylor scale). 5 presentations of 2 auditory stimuli varying only in intensity were given to each of 22 anxious and 22 nonanxious Ss. Increased intensity resulted in significant increases in amplitude and speed of reaction. Mean amplitude scores of the anxious group were significantly greater than those of the nonanxious group. A significant interaction was found between anxiety and intensity… . Significant sex differences were found on both measures. The results were discussed in terms of competing implicit response tendencies." (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)     

Cerebellar stimulation as an unconditioned stimulus in classical conditioning.

Implanted rabbits with chronic stimulating electrodes in white matter underlying lobule HVI of the cerebellar cortex. Stimulation elicited movements of the face or neck and, when paired with a tone CS, produced learning comparable to that seen with peripheral unconditioned stimulus/stimuli (UCS). CS-alone trials produced extinction. Reinstatement of paired trials produced reacquisition with savings. Additional groups received either explicitly or randomly unpaired CS–UCS trials before paired conditioning. Low-frequency responding during these sessions indicated that the paired training results were associative and not due to pseudoconditioning or sensitization. Explicitly unpaired sessions retarded learning on subsequent paired trials compared with groups that received either randomly unpaired or no CS–UCS preexposure. These results are interpreted in terms of the role of the cerebellum and associated pathways in classical conditioning of motor responses. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Learned helplessness as conditioned inattention to the target stimulus.

Learned helplessness theory explains the impaired performance that follows exposure to uncontrollable outcomes by assuming learned expectation of response-outcome independence that is transferred between tasks. Recent evidence has shown that introducing a second neutral stimulus, contingent on the offset of the uncontrollable stimulus, removes the subsequent interference. This finding has been claimed to support the view that the interference is a result of conditioned inattention rather than of the expectation of response-outcome independence. The conflicting explanations were examined in a series of 4 experiments, using a total of 202 students (undergraduates and nursing and physiotherapy students), that varied induction procedures (passive exposure or inescapability) and stimulus quality (aversive or nonaversive). All 4 experiments found the predicted interference, but only 1, in which passive exposure was combined with an aversive stimulus, obtained results supporting the conditioned inattention hypothesis. It is concluded that learned helplessness probably involves more than a single mechanism and that the passive exposure procedure may not be appropriate for demonstrating genuine helplessness deficits. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)