Preparedness and phobia: Effects of stimulus content on human visceral conditioning.

Conducted 6 experiments to test M. Seligman's (see PA, Vols 45:1675 and 48:1326) preparedness theory of phobia in human classical conditioning of skin conductance and heart rate responses with approximately 12 undergraduates. Conditioned stimuli (CSs) were photographs of plants, human artifacts, and phobia-relevant animals. Both aversive tactile and auditory unconditioned stimuli (UCSs) were assessed. Combined present results indicate that, consistent with results obtained by A. Ohman and colleagues in research conducted between 1975 and 1985 to test Seligman's theory, electrodermal extinction was slower to phobia-relevant stimuli than to other stimuli (and in the present study, was shown to depend on a tactile UCS); however, unlike the findings of Ohman and colleagues, when Ss were told that shocks would be discontinued, phobic CSs extinguished as readily as unprepared CSs. New evidence was obtained for a preparedness effect during acquisition trials: Only Ss receiving phobia-relevant stimuli developed an acceleratory cardiac conditioned response (CR). This acquisition effect was more reliable across experiments than the electrodermal extinction findings and showed less influence of CS—UCS "belongingness." Findings suggest that the preparedness effect is complexly determined and provide evidence that phobic stimuli occasion a unique pattern of conditioned visceral response. (48 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Classical differential and operant conditioning in rabbits (Oryctolagus cuniculus) with septal lesions.

12 normal New Zealand white rabbits and 12 with septal lesions received classical differential conditioning of the nictitating membrane response (NMR), followed by auditory generalization tests run in extinction. Although rate of acquisition and asymptotic responding to positive conditioned stimuli did not differ, septals responded more than normals to nonreinforced stimuli. Resultant decrements in differential conditioning could not be attributed to changes in auditory or shock thresholds or to increased spontaneous NMRs. Septals also responded at higher rates in both operant conditioning (barpresses reinforced with food pellets on a variable interval schedule) and extinction sessions. No difference in suppression in a passive avoidance task was found. Results are discussed in relation to R. A. McCleary's (1966) response disinhibition analysis of septal function, and an habituation hypothesis is considered. (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Modulation of the acquisition of the rabbit eyeblink conditioned response by conditioned contextual stimuli.

Three experiments were conducted to ask if conditioned emotional responses (CERs) controlled by contextual cues modulate the acquisition of eyelid conditioned responses (CRs) to discrete conditioned stimuli (CSs). Experiment 1 showed that 30-s auditory stimuli that were paired with aversive shocks to one paraorbital region or the other controlled discriminated CERs, as measured by potentiation of a startle response. In Experiments 2 and 3, similarly trained 30-s stimuli served as contexts in which 1,050-ms CSs were paired with a paraorbital unconditioned stimulus (US). Reinforced contexts both impaired (Experiments 2A and 2B) and facilitated (Experiment 3B) acquisition of the eyeblink CR, depending on the locus of the USs involved. The data are consistent with the interpretation that CERs controlled by contextual cues facilitate CR acquisition, but do so in the face of blocking effects of CR tendencies also conditioned to the contextual cues. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of hippocampal stimulation on acquisition, extinction, and generalization of conditioned suppression in the rat.

In 6 experiments, a total of 142 male Holtzman rats implanted with electrodes in the dorsal or ventral hippocampus received posttrial stimulation in training sessions with footshock reinforcement. Afterdischarges without overt seizures were consistently without effect on the rate of acquisition of suppression of licking during an auditory CS, although conditioning was retarded by the delivery of distracting stimuli following footshock. The rate of conditioning remained insensitive to elicitation of dorsal hippocampal afterdischarges (DHAD) despite subsequent alterations of session length, intertrial interval, and preexposure to the CS. However, faster extinction of suppression occurred following DHAD, suggesting a limited but essential role of the hippocampus in addressing stored information. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Bidirectional grapheme-phoneme activation in a bimodal detection task.

A divided attention paradigm was used to investigate whether graphemes and phonemes can mutually activate or inhibit each other during bimodal processing. In 3 experiments, Dutch Ss reacted to visual and auditory targets in single-channel or bimodal stimuli. In some bimodal conditions, the visual and auditory targets were nominally identical or redundant (e.g., visual A and auditory /a/); in others they were not (e.g., visual U and auditory /a/). Temporal aspects of cross-modal activation were examined by varying the stimulus onset asynchrony of visual and auditory stimuli. Cross-modal facilitation, but not inhibition, occurred rapidly and automatically between phoneme and grapheme representations. Implications for current models of bimodal processing and word recognition are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Responses of pigeon (Columba livia) Wulst neurons during acquisition and reversal of a visual discrimination task.

The avian visual "Wulst" is a target of the ascending thalamofugal visual pathway. In pigeons (Columba livia), lesion damage to the Wulst has little effect on simple visual discriminations, but impairs performance on tasks such as reversal learning. We recorded the responses of single Wulst neurons as pigeons were trained on the acquisition and subsequent reversal of a visual discrimination. Of the 64 units recorded, 54 (84%) displayed a significant difference in firing rate between some component of the task and the intertrial interval that separated trials. More important, 14 units (22%) displayed a significant change in firing rate exclusively to the S+ and/or S- as learning progressed either during acquisition or reversal. The responses of these 14 neurons indicate that learning during initial acquisition was as likely to correlate with a change in firing rate as during reversal, and some neuronal responses could be characterized as representing reward properties together with visual stimulus features. As such, responses of pigeon Wulst neurons indicate a role in representing aspects of learning as much as the physical/perceptual properties of visual stimuli. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Bait-shyness acquisition is impaired by VMH lesions that produce obesity.

Lesioned Carworth CFE female rats in the area of the ventromedial nucleus of the hypothalamus (VMH) before or after avoidance learning. Prelesioned Ss learned to avoid familiar saccharin-sweetened water associated with apomorphine less rapidly, and during extinction lost the avoidance more rapidly than controls. Ss lesioned after avoidance learning continued to avoid, and during extinction lost the avoidance at the same rate as controls. When given ad-lib food and water, lesioned Ss became obese. 1 tentative interpretation is that VMH-lesioned rats overrespond to environmental stimuli, including their food. This interferes with gustatory-visceral associations needed for satiety and bait-shyness acquisition. Another possibility is that overresponding to environmental stimuli and impaired gustatory-visceral associations are both direct consequences of VMH lesions. (32 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Garner and congruence effects in the speeded classification of bimodal signals.

The role of attention in speeded Garner classification of concurrently presented auditory and visual signals was examined in 4 experiments. Within-trial interference (i.e., congruence effects) occurred regardless of the attentional demands of the task. Between-trials interference (i.e., Garner interference) occurred only under conditions of divided attention when making judgments about auditory signals. Of importance, the data show congruence effects in the absence of Garner interference. Such a pattern has been rarely reported in studies of the classification of purely visual stimuli and contradicts theoretical accounts asserting that the effects share a common locus. The data question the notion that Garner classification reveals fundamental insights about the nature of the perceptual processing of bimodal stimuli. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of varied extinction conditions with alcoholics and social drinkers.

In a task analogous to excessive drinking behavior, 30 male alcoholics and 30 male social drinkers trained on a 100% rewarded button-pressing response received 1 of 3 extinction conditions: nonreward, simultaneous reward-punishment, and punishment only. Ss could discontinue responding at any time during the extinction phase. Alcoholics showed significantly greater resistance to extinction in the punishment and reward-punishment conditions, but not in the nonreward condition. No differences were found between groups during acquisition. Using an anticipatory punishment response model, an explanation of maladaptive operant responding in the alcoholic is suggested. (18 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Individual Differences in the Pattern of Habituation at 5 and 10 Months of Age.

Individual differences in pattern of habituation in fixation time and cardiac change to visual and auditory stimuli are described. Nearly half of the longitudinal sample at 5 months and almost 90% at 10 months did not display a monotonically decreasing habituation pattern over trials, a result that challenges the use of simple indices of response decline as measures of rate of information processing. A positive response to a novel stimulus at 5 and 10 months was observed only if an obvious peak response followed by a decline occurred during familiarization and (for 5-month-old subjects only) if the peak/decline occurred shortly before the introduction of the novel stimulus. Relative to 5 months, habituation patterns at 10 months were flatter and more irregular, and individual differences did not revolve around a few prototypical patterns. No evidence was observed for individual stability in type of habituation pattern across modality within an age or within modality across age, nor were there many correlates between pattern and demographic characteristics of the subjects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Transfer of noncorresponding spatial associations to the auditory Simon task.

Four experiments examined transfer of noncorresponding spatial stimulus-response associations to an auditory Simon task for which stimulus location was irrelevant. Experiment 1 established that, for a horizontal auditory Simon task, transfer of spatial associations occurs after 300 trials of practice with an incompatible mapping of auditory stimuli to keypress responses. Experiments 2-4 examined transfer effects within the auditory modality when the stimuli and responses were varied along vertical and horizontal dimensions. Transfer occurred when the stimuli and responses were arrayed along the same dimension in practice and transfer but not when they were arrayed along orthogonal dimensions. These findings indicate that prior task-defined associations have less influence on the auditory Simon effect than on the visual Simon effect, possibly because of the stronger tendency for an auditory stimulus to activate its corresponding response. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential contribution of dorsal and ventral medial prefrontal cortex to the acquisition and extinction of conditioned fear in rats.

The emotional reactivity of rats with lesions of the dorsal portion of medial prefrontal cortex (mPFC) was examined using a classical fear conditioning paradigm. Conditioned fear behavior (freezing responses) was measured during both the acquisition and extinction phases of the task. Lesions enhanced fear reactivity to both the conditioned stimulus (CS) and contextual stimuli during both phases, suggesting that dorsal mPFC lesions produce a general increase in fear reactivity in response to fear conditioning. M. A. Morgan, L. M. Romanski, and J. E. LeDoux (1993) found that lesions just ventral to the present lesions had no effect during acquisition of the same task and prolonged the fear response to the CS (but not the context) during extinction. Thus, both dorsal and ventral regions of mPFC are involved in the fear system, but each modulates different aspects of fear responsivity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stimulus–response overshadowing: Effects of signaled reward on instrumental responding as measured by response rate and resistance to change.

If every food reinforcer delivered on a VI schedule is preceded by a brief flash of light, rats leverpress for food more slowly than if light flashes are given independent of the food and their responding. This retardation in rate has been attributed to the overshadowing of the response–food association by the light–food association. Such an explanation assumes that response rate is positively correlated to the response association strength. Exps I and II investigated this account by using prefeeding and extinction procedures to test the strength of responding in 44 Long-Evans rats that had received food-correlated or random-light signals. Acquisition response rate was lower in the signaled condition (consistent with previous studies), but responding was more resistant to both extinction and satiation, regardless of whether the light cues were presented during the extinction/prefeeding phase. Exp III, with 27 Ss, revealed no difference between the signaled and random conditions either in terms of acquisition response rates or resistance to satiation when a VR schedule of reinforcement was used. Results are inconsistent with an overshadowing account of the acquisition rate difference. Instead, the signal seems to enhance the rat's sensitivity to the contingencies present on VI schedules. (44 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effect of differential hippocampal lesions and pre- and postoperative training on extinction.

Examined resistance to extinction of a food-motivated response in a total of 78 male albino Wistar rats with sham operations or bilateral dorsal hippocampal, ventral hippocampal, or combined dorsal and ventral hippocampal lesions in 2 experiments. Surgery occurred either before or after acquisition of the to-be-extinguished response. Ss with combined hippocampal lesions showed greater resistance to extinction than controls if acquisition occurred preoperatively, but less resistance if acquisition occurred postoperatively. Ss with ventral hippocampal lesions were affected in a similar manner but to a lesser degree by differential prior experience. In contrast, dorsal hippocampal-lesioned Ss exhibited no change in approach latency during extinction, irrespective of the timing of surgery. It is suggested that both ventral and combined hippocampal lesions interfere with the changing of an established approach "set." (French summary) (16 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Enhanced cue function of olfactory stimulation in mice with septal lesions.

Trained a total of 121 male hybrid normal mice and mice with septal lesions on a go-no-go discrimination task (multiple fixed interval of 15 sec, 15-sec extinction schedule) in 4 experiments. When the discrimination stimulus (the one which indicated to the S whether responding at the end of the interval would be reinforced) was a pellet of food (delivered at the start of the interval) or odor of food or non-nutritive substance (present throughout the 15-sec interval), acquisition of septum-damaged mice was enhanced. These lesions did not, however, alter performance when the discrimination was cued by a buzzer or flashing light. Results suggest that septal lesions produce an increased reactivity to olfactory stimuli and to stimuli associated with the delivery of food reinforcement. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pinna movements of the cat during sound localization

We measured the movements of the external ear, or pinna, using the magnetic search coil technique in cats trained to look at auditory and visual targets for a food reward. No behavioral contingencies were placed on pinna movements. Prominent pinna movements accompany eye movements when the animal orients to either auditory or visual stimuli. In visual trials the pinna movements are coordinated with eye movements, suggesting that they are part of the general orientation response of the animal. In auditory trials the pinna response was composed of two movements: short- and long-latency components. Whereas the long-latency component seemed to occur with the eye movement to the target, the short-latency component was coupled to the onset of the stimulus. The short-latency component ( approximately 25 msec) was highly asymmetrical, being largest in the pinna ipsilateral to the stimuli. In one animal it persisted after >10(5) trials.     

Specificity of process, response, and stimulus in behavioral bioassays.

Reported 3 experiments which studied aspects of the behavioral specificity of the "biochemical transfer" phenomenon. In Exp I, using 120 common goldfish, an acquisition extract facilitated acquisition but not extinction, while an extinction extract facilitated extinction but not acquisition. In Exp II, using 60 Ss from Exp I and 20 additional Ss, brain extracts facilitated an avoidance response only if they originated in donors that made that same response; extracts from donors that did not respond, although exposed to identical stimuli, did not modify recipient behavior. In Exp III, the biochemical transfer effect was found to be stimulus specific in 48 large and 111 small Ss. Results suggest that the extracts in question are behavior specific and do not generally affect behavior in a global excitatory or global inhibitory way. (15 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cross-modal equivalence in early infancy: Auditory–visual intensity matching.

To examine the hypothesis that young infants ignore differences between lights and sounds and instead respond to auditory and visual stimuli as more or less similar depending on their intensity, a cardiac habituation/dishabituation method with a test for stimulus generalization was employed. In 2 experiments, a total of 40 3-wk-old Ss were repeatedly presented with white-light followed by white-noise stimuli of different intensities. A U-shaped relationship between magnitude of cardiac response (CR) and loudness was found. In view of previous findings that without prior visual stimulation a monotonic increase in CR to the same range of auditory stimuli results, this finding of a significant quadratic relationship with loudness suggests that Ss were responding to the auditory stimuli in terms of their similarity to the previously presented visual stimulus. A separate group of 14 infants presented with a more intense visual stimulus exhibited a shift in the intensity at which a minimal CR occurred. Results of a study with 31 adults did not show any systematic relationship between CR and loudness, indicating that unlike infants, adults do not spontaneously make cross-modal matches of intensity. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Amygdala inactivation reverses fear's ability to impair divided attention and make time stand still.

The cognitive and emotional effects of amygdala or frontal cortex lesions were compared in rats trained to time both a 50-s visual signal paired with food and an embedded 10- or 20-s auditory signal that was paired with either appetitive (food) or aversive (footshock) outcomes. When both auditory and visual signals were paired with food, control and amygdalar-lesioned rats were able to divide attention and to time both signals simultaneously, whereas when the embedded auditory signal was paired with footshock, control rats were impaired in their ability to divide attention and were able to time only one signal at a time. In contrast, amygdalar inactivation blocked this fear-related impairment and allowed rats to time both signals simultaneously, whereas rats with frontal cortex lesions demonstrated sequential processing under all conditions. These results support the proposal that the frontal cortex exerts executive control over the allocation of attentional resources, but that under stressful conditions the amygdala is crucial for the emergence of fear-evoked increments in selective attention leading to deficits in the ability to time 2 or more signals simultaneously. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Marking effects in Pavlovian trace conditioning.

[Correction Notice: An erratum for this article was reported in Vol 13(3) of Journal of Experimental Psychology: Animal Behavior Processes (see record 2008-10750-001). The last sentence in the second paragraph of the Discussion on page 128 should read as follows: "A second possibility is that in the marked ITI group, the marking of irrelevant events in the middle of the intertrial interval promoted associations between those events and food, which then interfered with the learning of an association between SI and food."] In four experiments we investigated pigeons' acquisition of a successive discrimination with a trace autoshaping procedure. The conditioned stimuli were 5-s presentations of colored key lights, one of which was followed by food after a 5-s delay. In Experiment 1, which used spatially defined cues, we found that acquisition of differential responding to the reinforced cue was facilitated when a brief flash of light immediately followed both reinforced and nonreinforced cues. Experiment 2 found a similar enhancement by the added light flash in a purely visual discrimination. Experiment 3 found that the flash facilitated learning only when presented immediately after the discriminative cues, and not when it occurred immediately before the cues or at the time of reinforcement. A fourth experiment found this facilitation effect only when the flash and reinforcement occurred on the same trial. These results are interpreted in terms of marking: The flash enhanced learning because it triggered a backward scan through recent memory to search for possible predictors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)