Visual CS Research Articles

Undernutrition during the brain growth period of the rat significantly delays the development of processes mediating pavlovian trace conditioning

Pavlovian trace conditioning procedures allow one to assess the ability of animals to associate events that are temporally separated because the conditioned stimulus terminates prior to the occurrence of the unconditioned stimulus. We report that undernutrition during Postnatal Days 2-18 significantly delays the development of trace conditioning to a visual stimulus. Previously undernourished 20-day-old rats conditioned when no temporal interval separated the termination of the CS and US onset (0-s trace interval). However, it was not until the undernourished pups were 30 days old that they conditioned when the trace interval was 10 or 30 s. In contrast, control pups only 20 days old were able to condition when a 10-s trace interval separated the CS and US events, and 25-day-old control pups conditioned when the interval was either 10 or 30 s. These results suggest that undernutrition delays the development of processes that enable the rat to sustain a representation of a visual CS during the trace interval.

Alleviation of short-term forgetting: Effects of the CS− and other conditioning elements in prior cueing or as context during test

Exposure to a nonreinforced stimulus (CS−) from the same stimulus dimension as the target or reinforced stimulus (CS+) has been shown to facilitate the acquisition of a conditioned aversion to either a visual or olfactory CS+ that has been paired with footshock. The present series of experiments examined the influence of CS− exposure during conditioning on subsequent retention of the conditioned aversion. Experiment 1 established circumstances in which subjects expressed equivalent aversions to the CS+ immediately following training regardless of whether they were exposed to a CS− at the time of conditioning or testing. Experiment 2 indicated that when the interval between conditioning and testing was lengthened, a conditioned aversion to the CS+ was evident only in subjects exposed to the CS− at the time of conditioning and at testing. Experiment 3 indicated that the CS− served as an extremely effective cue for retrieval of the conditioning episode; exposure to the CS− prior to testing resulted in the expression of conditioning that was otherwise not evident. Collectively, these results provide general information about the necessary and sufficient conditions for the alleviation of forgetting, and establish specifically that the CS− is important not only in the acquisition of the aversion to the CS+, but also in retention and forgetting of this aversion.

Cross-modality transfer effects in conditioning-enhanced neophobia in chicks (Gallus domesticus): Evidence for the separability of novelty from specific stimulus characteristics

In this study, we investigated the separability of novelty from specific stimulus characteristics (e.g., color or taste quality) in the transfer of aversion effects. Ninety-six chicks (Gallus domesticus) received a novel visual (red water) or taste (3.0% vinegar) CS paired with an injection of lithium chloride or saline. The chicks were then tested for aversion to the CS or for conditioning-enhanced neophobia in response to a different novel visual cue (green water) or taste cue (1.0% saline). Aversions to the CSs were reliable and similar to each other. Reliable evidence of conditioning-enhanced neophobia occurred with respect to each test stimulus, irrespective of the type of CS, but conditioning with the vinegar CS produced reliably greater enhancement of neophobia than did conditioning with red water. For each CS, postconditioning neophobia was more persistent in testing with saline than with green water. The results for postconditioning neophobia suggested that novelty is a general stimulus property that is separable from specific stimulus characteristics.

Dissociation of visual and olfactory conditioning in the neostriatum of rats

In an experiment designed to demonstrate a double dissociation, the effects of bilateral electrolytic lesions of either the posteroventral or the ventrolateral regions of the neostriatum on the conditioned emotional response (CER) were examined. Posteroventral lesions impaired acquisition of the CER with a visual CS but not with an olfactory CS. Sham-operated posteroventral and ventrolateral lesioned animals acquired the visual CER normally. Ventrolateral lesions impaired acquisition of the CER with the olfactory CS but not with the visual CS. Sham-operated ventrolateral and posteroventral lesioned animals acquired the olfactory CER normally. In a second experiment the effect of post-training unilateral intrastriatal microinjections of (+)-amphetamine on acquisition of the visual and olfactory CERs was studied. Posteroventral injections improved retention of the visual, but not the olfactory CER. Ventrolateral injections improved retention of the olfactory, but not the visual CER. Saline and delayed (+)-amphetamine injection controls demonstrated that the improvement of retention in each case was a retroactive improvement of memory for the recently acquired CERs by (+)-amphetamine. These findings are consistent with previous reports of post-training memory facilitation mediated by dopaminergic function in the neostriatum. The results of both experiments are consistent with a regional functional heterogeneity hypothesis: the idea that anatomically linked areas of cortex and neostriatum process memories involving different stimuli in similar ways and that the integrity of these structures and their connections is necessary to establish and consolidate associative memory.

Rearing in response to a visual conditioned stimulus: An index of associative strength or of associability?

Two procedures for observing rearing behavior during a localized visual CS paired with an appetitive US were compared within subjects during classical conditioning and extinction procedures. When rearing was observed using the method and response definition described by P. C. Holland (1977, Journal of Experimental Psychology: Animal Behavior Processes, 3, 77–104), responding was acquired and maintained during conditioning trials in rats receiving paired presentations of the CS and US, but not in rats receiving the stimuli according to a “truly random” procedure. When rearing of the same rats was observed using the method and response definition described by H. Kaye and J. M. Pearce (1984, Journal of Experimental Psychology: Animal Behavior Processes, 10, 90–109), responding declined across conditioning trials in both groups. Furthermore, in extinction, rearing during the CS declined according to Holland's scoring method but was temporarily restored according to Kaye and Pearce's scoring. Observations of a second behavior, magazine responding, revealed essentially the same pattern of responding for both methods of scoring. These results support the position that the response criteria used by Holland and by Kaye and Pearce assess different components of behavior that occur in response to a visual CS, reflecting associative strength (i.e., a CR) and associability of the CS (i.e., an OR), respectively.

Associative aspects of conditioned analgesia evoked by a discrete CS

Four experiments with rat subjects assessed conditioned analgesia evoked by a discrete visual CS repeatedly paired with a shock US. In Experiment 1, rats that received CS-US pairings followed by a hot-plate test of pain sensitivity in the presence of the CS showed significantly longer response latencies than groups of rats receiving a variety of Pavlovian control procedures, including CS and US explicitly unpaired, CS-alone, US-alone, and apparatus-alone. Experiment 2 showed that two CS-US pairings were required for the CS to evoke conditioned analgesia and that additional CS-US pairings did not augment the observed analgesia. Experiment 3 demonstrated extinction of conditioned analgesia in groups that received CS-alone presentations. Experiment 4 found that conditioned analgesia established with the present procedures was unaffected by prior administration of the opiate receptor antagonist naloxone. Experiments 1 and 3 also demonstrated a number of situations in which freezing behavior (used to index conditioned fear) could be dissociated from hot-plate response latencies (used to index conditioned analgesia). These results are discussed in terms of how associative learning processes mediate acquisition of conditioned analgesia.

Cross-modal transfer as a function of similarities between training tasks in classical conditioning of the rabbit

The present experiments examined transfer of training from visual to auditory sensory modalities in classical conditioning of the rabbit’s nictitating membrane response. Experiment 1 examined transfer from initial training with a single visual CS to subsequent auditory discrimination training, and Experiment 2 examined transfer from visual discrimination training to auditory discrimination training. The major findings were that (1) initial conditioning of a visual CS facilitated the overall rate of CR acquisition to the auditory CSs separate from the requirements for discrimination learning (Experiments 1 and 2), and (2) initial visual discrimination training facilitated auditory discrimination learning (Experiment 2). Thus, the animals appeared to encode separately both contiguous CS-US relations and CS+ versus CS− relations during initial visual training. The results are discussed with respect to theories of extradimensional transfer.

Classical heart-rate conditioning and differentiation of visual CS with an appetitive UCS in pigeons

A tachycardic response was classically conditioned in thirsty pigeons using water as an unconditioned stimulus and localized lights as conditioned stimuli. This was successful in 6 out of 9 birds. In one experiment the subjects had their heads immobilized so that the positions of the stimuli within the visual field could be precisely specified. When the stimuli were shifted from the binocular to the monocular field and vice versa there was no initial transfer of a conditioned differentiation between a white and a green light.

Cross-Modal Transfer of Avoidance Learning in Rats

Cross-modal avoidance learning was studied in 32 male, albino rats initially trained with either a visual or auditory CS. Half of the rats trained with each CS were retrained with the opposite CS and the rest with the same CS. Analysis indicated that avoidance training with a CS in one modality improves shock-avoidance conditioning with a CS in another sensory modality.

Interference Effects in Acquisition of Avoidance Behaviors by Rats

Four groups of rats were given avoidance training either in a Skinner box with a light CS (Groups 1 and 2) or in a shuttlebox with a tone or a light CS (Groups 3 and 4). This was followed by avoidance training in either a shuttlebox with a tone or a light CS (Groups 1 and 2, respectively) or a Skinner box with a light CS (Groups 3 and 4). Shuttlebox-avoidance training with either a visual or an auditory CS interfered with subsequent lever-press avoidance with a visual CS. Lever-press avoidance with a visual CS interfered with shuttlebox avoidance with an auditory CS but had little effect on subsequent shuttlebox avoidance with a visual CS. These results are in marked contrast with those of Ayres, Benedict, Glackenmeyer, and Mathews (1974) who found interference effects across response systems only in unsignalled situations.

Control of conditional discrimination performance by CS-evoked event representations

The ability of visual CSs previously paired with flavored substances to substitute for those substances as conditional discriminative cues was examined in two Pavlovian appetitive conditioning experiments using rat subjects. In Experiment 1, a visual stimulus was first paired with the delivery of a sucrose solution. Then the rats were trained in conditional discrimination tasks in which sucrose delivery alone served as a conditional cue signaling whether or not a subsequent tone would be reinforced with food pellets. Subjects rapidly acquired discriminative performance to the tones, especially in a feature-negative condition in which sucrose delivery signaled when the tone would not be reinforced. In a subsequent test in which neither food nor sucrose was delivered, presentation of the visual CS also controlled discriminative performance to subsequently presented tones. Experiment 2 showed the ability of a visual CS to substitute for a flavored substance as a conditional cue to be highly stimulus specific. Experiment 2 also showed that a flavored substance was less effective as a conditional cue when it was made to be expected by preceding it with a previously associated visual signal than when it was made to be surprising by preceding it with a visual stimulus signaling another flavored liquid. These results indicate that CS-evoked representations of events can substitute for those events themselves in the control of previously established conditional discrimination performance.

Within-signal learning in autoshaping

Four experiments explored the formation of associations among elements of a compound visual CS in an autoshaping preparation using pigeon subjects. Experiment 1 found evidence for such associations when the compound was presented without food reinforcement. Experiments 2 and 3 demonstrated that compounds embedded in procedures that produce blocking and conditioned inhibition also developed associations among their elements. Experiment 4 found, using a conditional discrimination procedure, that such within-signal associations were weakened, but not eliminated, by the presentation of food reinforcement at the end of the compound. These results suggest a pervasive role for within-signal associations across a variety of conditioning procedures that have been given central roles in current theories of conditioning.

On the manifestation of stimulus-directed behavior in the rat

The results of a three-phase autoshaping experiment with rats is reported. In Phase 1, subjects were exposed either to a paired or an unpaired arrangement of a visual CS and food. These treatments produced no differential contact with the visual stimulus, but paired rats were found to display greater approach to the site of food delivery than were unpaired subjects during the CS. In Phase 2, all subjects were given identical discrete-trials (FR 6) training with a different visual stimulus as an SD. In the final test stage, a choice procedure was employed, involving the simultaneous presentation of both CS and SD. Percent responding to the CS was greater for paired than for unpaired rats in this phase. These findings were interpreted as support for the view that the form of terminal contact with a signal for food is dependent upon the nature of the learned or innate behaviors that compose the organism’s normal food-getting sequence.

Heart rate conditioning in young infants using a visual conditional stimulus

Trace heart rate conditioning was evaluated in 16 infants having a mean age of 4.5 months. The Experimental Group received a 3-sec blinking light pattern as the CS, followed by a 3-sec interstimulus interval (ISI), and 3-sec tone as the UCS. The Control Group received an equal number of presentations of the CS and UCS at randomized intervals and in a randomized order. The acquisition of a conditioned deceleration during the period which included the visual CS and the ISI was demonstrated only in the Experimental males. Response differences were also found in the absence of the auditory UCS, with only Experimental females exhibiting a deceleration.

Autonomic classical conditioning as a function of awareness of stimulus contingencies

Two groups of 32 college students were presented compound CSs (lights and tones presented simultaneously) during a classical conditioning paradigm. By means of a masking task and verbal instructions, a partially informed group was made aware of only the visual CS's contingency with the UCS, while a fully informed group was made aware of both the visual and auditory contingencies. Autonomic indices of conditioning (electrodermal responses, heart rate, and digital pulse volume) were later measured to the individual component CSs and to various compound CSs. It was found that: (1) the partially informed group exhibited conditioning exclusively to the visual CS+ and to compounds which included the visual CS+, while (2) the fully informed group exhibited conditioning to both visual and auditory CS+s. The results confirm the importance of awareness in human autonomic discrimination classical conditioning. It is suggested that human autonomic conditioning may be usefully conceptualized as an information processing task with the autonomic indices of conditioning reflecting central cognitive processes.

Species Differences in Long-Term Discriminated Avoidance in Fish

Summary Four species of fish (N =12 each)—goldfish (Carassius auratus), mollies (Mollienesia sphenops), swordtails (Xiphophorus helleri), and gouramies (Helostoma temmincki)—were given 20 trials a day of avoidance conditioning to a visual CS in an aquatic shuttlebox for a minimum of 12 days and continuing to 30 days until a criterion of 17 avoidances in 20 trials had been reached. Species differences in trials to reach criterion reflected the number of fish within each species which failed to reach criterion. While all goldfish reached criterion quickly, a few swordtails required many trials, and some mollies and gouramies did not reach criterion in 30 days.

Directed approach responses and positive conditioned suppression in the rat

Three experiments evaluated an alternative to accounts of positive conditioned suppression that stress central (i.e., motivational or emotional) states. This “competing-response” interpretation was tested by analyzing directed movements that develop in rats during a visual or an auditory stimulus (CS) that signals an appetitive reinforcer (US) in a situation where the subject is also emitting an instrumental response for food. In each experiment, positive conditioned suppression (i.e., a reduction in the rate of such instrumental responding during CS presentations) was accompanied by responses directed toward the CS source and/or the US-delivery site. In Experiment 1, a diffuse (auditory) CS signaled a US delivered at some specific place in the chamber and rats approached the US-delivery site during CS. In Experiments 2 and 3, the spatial proximity of a localized visual CS and US-delivery site determined whether CS-directed or US-directed behavior predominated during the CS. The results suggest that the topographies of conditioned responses on any positive conditioned suppression procedure depend upon the spatial arrangements of features that elicit and support these behaviors. They further suggest that the identification of these features and their spatial arrangements is necessary for the analysis of appetitive classical-instrumental interactions.

Central cholinergic blockade by scopolamine and habituation, classical conditioning, and latent inhibition of the rabbit’s nictitating membrane response

Rabbits injected with scopolamine hydrobromide (1.5 mg/kg) were contrasted with control animals injected with scopolamine methylbromide or saline in terms of habituation of the unconditioned nictitating membrane response (NMR), classical defensive conditioning, and latent inhibition using auditory and visual conditioned stimuli. Scopolamine hydrobromide disrupted classical conditioning in comparison with drug controls, but had no adverse effects on habituation of the unconditioned reflex or on latent inhibition. The drug also raised thresholds of the auditory (but not visual) CS for eliciting the conditioned NMR. Results were discussed in terms of presumed cholinergiclimbic system involvement in Pavlovian conditioning and inhibition.

The effects upon food-reinforced pecking and treadle-pressing of auditory and visual signals for response-independent food

Seven pigeons whose key-pecking was maintained by food reinforcement on a differential-reinforcement-of-low-rates 12-sec limited-hold 4-sec schedule and 12 other pigeons whose treadle-pressing was maintained by the same schedule received appetitive Pavlovian conditioning trials superimposed upon the instrumental baseline. Half the birds in each group received a tone as the CS, and the other half received a stimulus change on the key. Each CS was 20 sec long, and was immediately followed by 10-sec access to grain. The visual CS markedly facilitated the rate of pecking on the key for the birds whose baseline response was pecking. The visual CS produced auto-shaping of the key-peck and tended to produce suppression of treadle-pressing for the birds whose baseline response was treadle-pressing. The auditory CS produced inconsistent effects across birds regardless of the baseline response. In all cases the conditioned effects extinguished when response-independent food was omitted.

Retrograde amnestic effects of inferotemporal and amygdaloid seizures upon conditioned suppression of lever-pressing in monkeys

Seizures induced electrically in the inferotemporal cortex, as monitored by EEG recording, produced retrograde amnestic effects upon the development of conditioned suppression of lever-pressing to a visual CS paired with shock US but not to a similarly paired auditory CS. The afterdischarges, which propagated to the amygdala among other structures, appeared to interfere with the association of the visual CS with the noxious US without blocking retention of information about the noxious US itself. By contrast, seizures induced in the amygdala, which showed a more variable pattern of propagation to inferotemporal cortex, produced no apparent retrograde amnestic effects.