The interaction of memories in the rat: Effects on short-term retention performance

In four experiments, rats were tested for short-term retention of a target spatial location either with or without prior exposures to alternate spatial locations in a T-maze. In all cases, exposure to alternate locations prior to exposure to the target location impaired retention of the target. This impairment increased as the number of exposures to the alternate location was increased, and the impairment decreased as the interval between alternate and target exposures was increased. In no case was the magnitude of the impairment found to increase as the retention interval was lengthened.     

The alleviation of short-term retention decrements with reactivation

Retention of spatial information by rats was shown to decrease significantly over a 90-sec retention interval. However, this decrement was alleviated significantly when a reactivation or cueing treatment was presented during the 90-sec interval. Further, the rate of forgetting following reactivation was shown to be similar to that which occurs following original information input. The implications of these findings for information loss models of forgetting were discussed.     

The effectiveness of imagery and sentence strategy instructions as a function of visual and auditory processing in young school-age children

The relationship between auditory and visual processing modality and strategy instructions was examined in first- and second-grade children. A Pictograph Sentence Memory Test was used to determine dominant processing modality as well as to assess instructional effects. The pictograph task was given first followed by auditory or visual interference. Children who were disrupted more by visual interference were classed as visual processors and those more disrupted by auditory interference were classed as auditory processors. Auditory and visual processors were then assigned to one of three conditions: interactive imagery strategy, sentence strategy, or a control group. Children in the imagery and sentence strategy groups were briefly taught to integrate the pictographs in order to remember them better. The sentence strategy was found to be effective for both auditory and visual processors, whereas the interactive imagery strategy was effective only for auditory processors.     

Reminder-induced recovery from blocking as a function of the number of compound trials

Conditioned lick suppression in rats was employed to examine changes in the associative status of a blocked stimulus as a function of the number of compound stimulus conditioning trials. In each of two experiments, prior tone-footshock pairings produced similar blocking of conditioned responding to the light element of a tone-light compound when either two or six compound trials were used. In experiment 1, two exposures to the light alone in a dissimilar context during the retention interval, i.e., a reminder treatment, resulted in a restoration of responding to the light which was complete and similar for animals receiving two or six compound trials. This indicated that latent acquisition with respect to the blocked stimulus was largely complete after two compound trials. Because of a potential ceiling effect for reminder-induced recovery from blocking, Experiment 2 employed an attenuated reminder (one light exposure). This reminder reversed the blocking when six, but not when two, compound trials were used. These results suggest that, after latent acquisition to the blocked stimulus is complete, the blocked stimulus continues to be processed during additional compound stimulus conditioning trials, with a consequent latent facilitation of retrieval of associations to the blocked stimulus.     

Contextual potentiation of acquired behavior after devaluing direct context-US associations

In two experiments, water-deprived rats were exposed to tone-footshock pairings in a particular conditioning context. In Experiment 1, the training parameters were selected on the basis of parametric pilot data so as not to produce direct associations between the conditioning context and footshock. Despite independent evidence of no appreciable direct association between the conditioning context and footshock, animals tested in the conditioning context exhibited more lick suppression to the tone than other animals tested with the tone outside of the conditioning context. Thus, the conditioning context potentiated suppression to the tone in the absence of appreciable fear of the conditioning context. In Experiment 2, training parameters were used that permitted the formation of direct associations between the conditioning context and footshock; however, for half the animals, these associations to the context were then extinguished. With the tone absent, a comparison of extinguished animals tested either in the conditioning context or outside the conditioning context detected no differences in suppression, demonstrating the effectiveness of the extinction manipulation. However, other animals also subjected to extinction of direct context-footshock associations displayed greater suppression to the tone within the conditioning context than comparable animals tested outside the context. Collectively the data indicate that the superior retention-test performance seen within the training context can arise both from the commonly assumed direct associations between the training context and the unconditioned stimulus and from the potentiation by the training context of the associations between the nominal conditioned stimulus and unconditioned stimulus.     

The effects of single-component extinction of a three-component serial CS on resistance to extinction of the conditioned avoidance response

Central to a fear interpretation of how avoidance responses are maintained in the absence of further CS-UCS pairings is the underlying assumption of an existing gradient of fear across the CS-UCS interval. Extrapolations based on this gradient lead to a number of differential predictions concerning the topography of avoidance responding during extinction. The present research was concerned with the differential effects of extinguishing separate components of the CS complex upon responding to the complete CS complex during extinction. In Phase 1 of the study, rats were classically conditioned to a three-component serial CS (S₁/S₂/S₃) followed by shock. Each subject was then given avoidance training in a one-way apparatus to a criterion of one successful avoidance. In Phase 2, subjects were divided into four groups, with three of the groups receiving nonreinforced exposure for 25 trials to one of the components of the serial CS (S₁, S₂, or S₃). The fourth group (S₀) was exposed for the same period of time to the apparatus cues. In Phase 3, the total stimulus complex was reintroduced in its original order, and animals were tested until extinction of the instrumental response was reached. The results are consistent with the hypothesis that a fear gradient exists in extinction and decreases in magnitude as the distance from the point of UCS onset increases.     

Alleviating forgetting of active shock-avoidance by apparently unrelated food presentations

A series of four experiments investigated why forgetting of an active shock-avoidance response was reduced when an apparently unrelated appetitive experience occurred both prior to avoidance training and during the retention interval between training and testing. Experiments 1 and 2 demonstrated the reliability of the phenomenon and found that a sufficient condition for the effect was the presentation of food from a pellet dispenser (not an operant response per se). Experiment 3 demonstrated that the effect was not the result of enhanced activity. Experiment 4 showed that forgetting was still reduced when the appetitive experience occurred only prior to active avoidance or only during the retention interval. The results are discussed in regard to the reinstatement of the reinforcer representation.     

Alleviation of forgetting of discrimination learning

Reactivation treatments intended to alleviate forgetting in rats were tested in two discrimination tasks—instrumental learning with brightness or with spatial location as the discriminanda. For memories acquired 28 days earlier, forgetting was alleviated with both tasks when testing was preceded by certain reactivation treatments. Therefore, the generality of the effectiveness of reactivation treatments for alleviating forgetting is extended to include discrimination learning and response measures other than go, no-go behavior.     

Avoidance extinction in goldfish

Independent groups of goldfish trained to avoid shock in a shuttlebox situation were presented with several extinction procedures in which the relationships between the conditioned stimulus and shock were altered and/or response contingencies removed. Random shock presentations, equivalent to the number of shocks received during avoidance acquisition, resulted in response decrements similar to those obtained when the conditioned stimulus was presented alone. Pairing the conditioned stimulus with shock on every trial, however, served to maintain response levels. When response-contingent punishment was superimposed upon these Pavlovian pairings, performance was facilitated slightly although punishment alone resulted in somewhat faster response reduction than that produced by exposure only to the conditioned stimulus. Extinction of avoidance responding produced by exposure to the conditioned stimulus alone was dependent on the total duration of exposure and independent of both number of stimulus onsets and response prevention. These experiments demonstrated that, in general, the procedures used to reduce avoidance responding in rats were equally effective for goldfish, with one exception: the introduction of a Pavlovian contingency following avoidance acquisition, making the previously avoidable shock unavoidable, maintained response probabilities near previously established levels.     

Dual effects of response blocking following avoidance learning

It was shown that either enhanced or decreased avoidance responding by rats could be produced by the same response blocking procedure occurring after avoidance training. The particular result produced depended on (1) the duration of the blocking trial and (2) when during the retention interval the blocking trial occurred. Results were interpreted in terms of a memory reactivation explanation and implications for the therapeutic uses of extinction were discussed.     

Mechanisms for the cueing phenomenon: The addition of the cueing context to the training memory

A series of three experiments was run to test the hypothesis that when animals are exposed to a cue from prior training, the context in which cueing occurs becomes associated with the training memory. The first experiment demonstrates that when rats are trained to avoid in one context and then are tested in a different context performance is reduced. Experiments 2 and 3 demonstrate that this performance deficit can be alleviated by cueing the rats in the test context prior to testing. The data suggested that the improved performance does not seem to result from the association of the cueing context with a fear response. These results are discussed in relation to the context addition hypothesis.     

Sufficient conditions for an ordered-ring isomorphism onto a positive subinterval: A lemma for polynomial measurement

This paper discusses a sufficient set of conditions for a structure to be ordered-ring isomorphic to a positive subinterval of the real numbers. It extends our previous results concerning bounded versions of Hölder's Theorem (Falmagne, 1971). The main result can serve as a basic lemma for establishing representation theorems in polynomial conjoint measurement when the empirical sets contain neither large elements nor ones close to the natural zero.     

Reminder-induced recovery of associations to an overshadowed stimulus

The possibility of reversing the deficit produced by overshadowing through the use of memory reactivation was investigated. Using lick suppression as a measure of associative strength, water-deprived rats were conditioned in a Pavlovian paradigm which produced reliable overshadowing of a flashing light by a tone. It was found, however, that exposure to the overshadowed stimulus outside of the conditioning context during the retention interval (reminder treatment) caused an increase in lick suppression during testing in animals that had undergone overshadowing, relative to nonreminded overshadowed animals. Subjects that received the reminder treatment but were conditioned without overshadowing showed no increase in lick suppression. Additional control groups ensured that the increase in suppression observed in the overshadowed subjects following reminder treatment was not due to nonspecific fear. The results suggest that the performance deficit produced by overshadowing is due at least in part to a reversible failure to efficiently retrieve associations to the overshadowed stimulus at the time of testing, rather than a failure to form those associations during conditioning.     

Forgetting of recently acquired or recently reactivated memories

Four experiments compared the rates of forgetting following acquisition of a conditioned aversion and following a reactivation treatment given long after conditioning had been completed. The “reactivation treatment” consisted of a single presentation of the unconditioned stimulus, a procedure known to reinstate, following substantial forgetting, the behavior seen immediately after conditioning. It was first determined that the decrement in performance 1, 3, or 7 days later tended to be more rapid just after original conditioning than following a reactivation treatment given 27 days after conditioning. Subsequent experiments confirmed that the forgetting seen 3 or 7 days after original conditioning was in fact greater than forgetting 3 or 7 days after the reactivation treatment that had followed conditioning by 27 days; also, tests permitted rejection of the hypothesis that this effect could be attributed to nonassociative (systemic) consequences of the conditioning situation. Finally, tests indicated that retention 24 hr after a reactivation treatment was significantly better if the reactivation treatment followed conditioning by 27 days than if it were given just 3 min or 24 hr after conditioning. The central observation emerging from this study, that forgetting is more rapid following original learning than following a temporally remote reactivation treatment, was discussed in terms of potential interactions between the age (or accessibility) of a memory and processes that might be instigated by a reactivation treatment.     

Stimulus factors and listening strategies in auditory memory: A theoretical analysis

A theory for the temporal course of perceptual coding during auditory short-term memory tasks is described. A low-level “sensor” and a high-level “identifier” process item and order information from stimulus word-strings. Both word durations and interword pauses are needed for this processing, and if adequate processing time is unavailable, perceptual delays will lead to degraded recall performance. Stimulus parameters and subject strategies interact to determine the quality and the order in which stimulus items are coded. These hypotheses are supported both by experiments using grammatical sentences and those using lists of unrelated words.     

Stimulus factors and listening strategies in auditory memory: An experimental demonstration

Three experiments are reported in which digits spoken at different rates were recalled and monitored. In Experiment I, digits to be recalled were embedded in varying levels of noise. In Experiment II noise was presented only during the inter-digit intervals, either to the same or to the opposite ear as the digits. In Experiment III Ss monitored these sequences for a specified digit and reported its successor. Stimulus rate and signal-to-noise ratio affected perceptual processing time, as evidenced by the frequency and relative proportion of item and order errors. These stimulus factors induce listening strategies that influence the shape of the serial position curve and that persist after stimulus conditions are changed. The data are consistent with a two-stage processing model for the temporal course of speech perception and the nature of listening strategies.     

Effects of sexual versus fear arousal on alcohol consumption in college males

To compare the effects of pleasant and aversive arousal on alcohol consumption, 18 male undergraduates had three weekly sessions to separately view erotic, mutilation or neutral slides in a simulated memory experiment. Following exposure to the slides, they received access to alcoholic and nonalcoholic beverages, which were presented to half the subjects in a taste rating task, and to half as the result of engaging in an operant lever-press task. Subjects believed these tasks to be distractors during a purported retention interval. Self-report instruments and basal skin conductance confirmed the success of the affective manipulations. However, only the subjects using the taste task after viewing erotic slides significantly increased alcohol consumption. These results question a tension reduction model of drinking and qualify the contribution of autonomic arousal to motivation for drinking.