Effects of reserpine on retention of escape reversal in mice: absence of state-dependent learning.

A discriminated escape training paradigm was used to study the effects of reserpine on learning and memory in mice. Intraperitoneal injection of reserpine before reversal training had no effect on acquisition but did produced a time-and dose-dependent impairment of retention test performance 10 days later. These results suggested that reserpine may have interfered with some aspect of memory storage. Retention impairments observed when a 2.0 mg/kg reserpine injection was given 2 hr before reversal training were not attenuated by readministering the drug before testing, a finding that provides no support for a state-dependency interpretation. Furthermore, animals treated with reserpine exhibited inferior retention of previous training, regardless of the pharmacological state present during that learning. This was interpreted as a drug-induced impairment of memory retrieval. In addition, performance during the initial discriminated escape training session suggested that reserpine may also impair acquisition under some conditions. In the last experiment, it was found that when the catecholamine precursor L-dihydroxyphenylalamine (100 mg/kg) and the indole amine precursor D,L-5-hydroxytryptophan (125 mg/kg) were both given after reserpine treatment, subsequent retention performance was not significantly impaired. The results are discussed in terms of the possible roles of biogenic amines in arousal, learning, and memory.     

Attribution theory, insomnia, and the reverse placebo effect: a reversal of Storms and Nisbett's findings.

Storms and Nisbett found that insomniacs got to sleep faster than usual on nights when they took placebos believed to be arousal pills. Our study attempted: (a) to replicate the reverse placebo effect using a method of measurement considered more accurate than the original technique, (b) to evaluate the effect of an arousal pill therapy after therapy is discontinued, and (c) to clarify which of two hypotheses better accounts for the effect. Using 42 insomniacs, the design varied whether pills were administered (pill) or withheld (no pill) and whether or not high justification was provided for taking the pills. The high-justification-pill and the high-justification-no-pill groups were given information intended to justify their participation, while the no-justification-pill and no-pill-no-justification groups were treated like the original arousal and control groups. Instead of a decrease in latency to sleep, the no-justification-pill group but not the high-justification-pill troup displayed a typical placebo reaction on nights they took the pills. Our results cast suspicion on the original finding. The lack of response by the high-justification-pill group is discussed in terms of Bem and Kelley's views of attribution theory.     

The effect of training procedures on the overlearning reversal effect in young children

The performance of 80 preschool children on a reversal problem was studied as a function of amount of training and type of training procedure used during acquisition and reversal. In the extinction phase of reversal learning, subjects given a correction procedure during the reversal problem made fewer perseverative errors than subjects given noncorrection. In the reversal midplateau phase of reversal learning, overtraining facilitated reversal learning for subjects receiving noncorrection during the acquistion problem, but not for subjects receiving correction. A shift in training procedure between acquisition and reversal increased the number of subjects who reached criterion immediately after perseveration. Since these results are difficult to explain in terms of traditional learning theories, an alternative response-switching strategy explanation was proposed.     

Inhibiting effect of D1, but not D2 antagonist administered to the striatum on retention of passive avoidance in the chick

The avian lobus parolfactorius, equivalent to the medial striatum (caudate-putamen) of mammals, has been shown to be of crucial importance in passive avoidance training in day-old domestic chicks, where the aversive stimulus is the bitter tasting substance methylanthranilate. Here we report that the specific D1 antagonist SCH23390, injected into the lobus parolfactorius of day-old chicks (Gallus domesticus) prior to training, impaired performance on testing 30min post-training at low doses (0.5 and 25nmol). Sulpiride, a D2 antagonist, had no significant effect on performance in comparable doses. The early D1 activation may signify an essential mechanism leading to storage itself or to the canalisation of the relevant association to a permanent store.     

Effect of peripherally administered lipopolysaccharide (LPS) on GTP cyclohydrolase I, tetrahydrobiopterin and norepinephrine in the locus coeruleus in mice

Lipopolysaccharide (LPS), an endotoxin released from the outer membranes of Gram-negative bacteria, triggers cells to synthesize and release inflammatory cytokines that may progress to septic shock in vivo. We found that LPS enhances tetrahydrobiopterin (BH4) biosynthesis by inducing the biosynthetic enzyme GTP cyclohydrolase I (GCH) in vitro in the mouse neuroblastoma cell line N1E-115. Furthermore, we observed that gene expression of GCH in the locus coeruleus (LC) in mice was enhanced by peripheral administration of LPS, resulting in increased concentrations of BH4, and norepinephrine, and its metabolite 4-hydroxy-3-methoxyphenylglycol (MHPG). These results suggest that tyrosine hydroxylase (TH) activity is increased by increased content of BH4 due to enhanced mRNA expression of GCH in the LC resulting in the increase in norepinephrine in the LC during endotoxemia. LPS in blood may act as a stressor to increase norepinephrine biosynthesis in the mouse LC.     

The effect of cue-familiarity, cue-distinctiveness, and retention interval on prospective remembering

Five experiments investigated the effects of cue familiarity, cue distinctiveness, and retention interval on prospective remembering. Results showed that (1) performance in a prospective memory task is facilitated when the cue is unfamiliar and/or distinctive; and (2) it is impaired by 3-minutes' delay between the instructions and the task (Experiment 1). A beneficial effect of distinctiveness was also found when perceptual rather than semantic distinctiveness was tested (Experiment 2). Experiments 3 and 4 ruled out the hypotheses that “unfulfilled expectancy” of an event (i.e. non-appearance of the cue during training) (Experiment 3), or some sort of “habituation” in the target context (Experiment 4), may have caused the low performance observed in the delayed conditions. Finally, results from Experiment 5 showed that delay negatively affected prospective remembering when it was filled with either a demanding interpolated activity (practice in a STM task) or an undemanding motoric activity (repetitive hands movements). Unfilled delay and an undemanding verbal activity (counting) were found not to affect prospective memory. Implications for the mechanisms underlying prospective remembering are discussed.     

The contributions of encoding,retention, and recall to the Hebb effect

The article reports an experiment testing whether the Hebb repetition effect—the gradual improvement of immediate serial recall when the same list is repeated several times—depends on overt recall of the repeated lists. Previous reports which suggest that recall is critical confound the recall manipulation with retention interval. The present experiment orthogonally varies retention interval (0 or 9 s) and whether the list is to be recalled after the retention interval. Hebb repetition learning is assessed in a final test phase. A repetition effect was obtained in all four experimental conditions; it was larger for recalled than non-recalled lists, whereas retention interval had no effect. The results show that encoding is sufficient to generate cumulative long-term learning, which is strengthened by recall. Rehearsal, if it takes place in the retention interval at all, does not have the same effect on long-term learning as overt recall.     

The effect of flumazenil on acquisition, retention, and retrieval of spatial information.

The effect of flumazenil, a benzodiazepine-receptor antagonist, was evaluated in a spatial-reference memory procedure in a water maze. Flumazenil (1.0, 3.0, and 10.0 mg/kg, ip) did not modify acquisition of spatial information. Retention was similar between control and experimental rats 24 h after the training phase, as all groups showed bias to the target quadrant in a free swim trial. However, 10 days later, only flumazenil-injected rats (3.0 mg/kg) showed bias to the target quadrant. Flumazenil did not affect retrieval of spatial information in a group of well-trained rats. These results suggest that a benzodiazepine-receptor mediated endogenous mechanism is activated during learning of spatial tasks and that its blockade facilitates retention of spatial information.     

The effect of instructions on the apparent reversal of rotary motion in depth

This study concerns experimental investigation of the effect of instructions on the apparent reversal of rotary motion in depth. It was found that subjects instructed to report apparent reversals of an elliptical shape signalled more reversals than subjects who were instructed to report the non-occurrence of reversals. This difference increased over four trials. When the stimulus object was a trapezium window instructions to report reversals led to a higher rate of reversals than did instructions to report non-occurrence, but this difference did not increase significantly over trials.     

The effect of reinforcement probability on time discrimination in the midsession reversal task

We examined how biasing time perception affects choice in a midsession reversal task. Given a simultaneous discrimination between stimuli S1 and S2, with choices of S1 reinforced during the first, but not the second half of the trials, and choices of S2 reinforced during the second, but not the first half of the trials, pigeons show anticipation errors (premature choices of S2) and perseveration errors (belated choices of S1). This suggests that choice depends on timing processes, on predicting when the contingency reverses based on session duration. We exposed 7 pigeons to a midsession reversal task and manipulated the reinforcement rate on each half of the session. Compared to equal reinforcement rates on both halves of the session, when the reinforcement rate on the first half was lower than on the second half, performance showed more anticipation and less perseveration errors, and when the reinforcement rate on the first half was higher than on the second half, performance showed a remarkable reduction of both types of errors. These results suggest that choice depends on both time into the session and the outcome of previous trials. They also challenge current models of timing to integrate local effects.     

The effect of pictures on the retention of novel words and prose passages

The effect of pictures on the retention of novel words and prose passages was examined for both good and poor readers. The findings suggest that for both groups of subjects the presence of pictures enhances recall of the prose passages but has no effect on the recognition and pronunciation of novel words. Systematic differences in the strategies used by good and poor readers were also observed.     

Phonological similarity in free and serial recall: The effect of increasing retention intervals

The phonological similarity effect (or acoustic confusion effect) consists of poor serial recall performance for lists composed of similar‐sounding words compared to lists of dissimilar‐sounding items. Building on the work of Nairne and Kelley (1999), the extent to which this classical verbal short‐term memory effect changes over the course of a retention interval was investigated. The impact of the phonological similarity on memory performance over time was compared in three paradigms: order reconstruction, serial recall, and free recall. Participants were presented with two blocks of 15 lists composed of five monosyllabic words, one block containing phonologically similar words and the other phonologically distinct words. Recall occurred either after 2, 8, or 24 seconds retention interval filled with a digit shadowing task. Our results confirmed and extended those of Nairne and Kelley. In order reconstruction and serial recall tasks, a classical phonological similarity effect (i.e., decrement in performance with similar lists) was observed for the 2‐s retention interval. This effect disappeared after a brief period of digit shadowing (i.e., 8‐s delay) and a beneficial effect of similarity was observed for the 24‐s retention interval. In the free recall task, the phonological similarity produced better performance whatever the delay between presentation and recall. Those results are discussed in the light of Nairne's (1990a) feature model and confirm the role of item‐specific and inter‐item processes in order reconstruction, serial recall, and free recall. L'effet de similarité phonologique se manifeste par une performance de rappel plus faible lorsque les listes sont composées de mots dont la sonorité est proche que lorsque les mots sont de sonorité éloignée. Sur la base de la recherche de Nairne et Kelley (1999), nous nous sommes intéressés à la manière dont évolue cet effet classique de mémoire à court terme verbale dans le temps, C'est‐à‐dire à L'issue d'intervalles de rétention de durées variables. L'impact de la similarité phonologique sur la performance mnésique a été évaluée sur la base de trois paradigmes, la reconstruction de L'ordre, le rappel sériel et le rappel libre. Les participants ont été soumis à deux blocs de 15 listes comportant 5 mots monosyllabiques, un bloc comprenant des mots similaires phonologiquement et un bloc comprenant des mots dissimilaires phonologiquement. Le rappel est demandé après un intervalle de rétention d'une durée de 2, 8 ou 24 secondes durant lequel une tâche de shadowing de chiffres est proposée. Nos résultats confirment et étendent ceux obtenus par Nairne et Kelley. Pour les tâches de reconstruction de L'ordre et de rappel sériel, un effet de similarité phonologique classique (i.e., chute des performances pour les listes similaires) est observé avec un intervalle de rétention de 2 secondes. Cet effet disparaît après une courte période consacrée au shadowing de chiffres (i.e., 8 secondes) et un effet bénéfique de la similarité est observé pour un intervalle de rétention de 24 secondes. En rappel libre, la similarité phonologique provoque une amélioration des performances quel que soit le délai entre présentation et rappel. Ces résultats sont discutés à la lumière du modèle des traits de Nairne (1990a). Ils confirment le rôle des traitements spécifiques à L'item et des traitements inter‐items lors de tâches telles que la reconstruction de L'ordre, le rappel sériel et libre. El efecto de la similitud fonológica (o efecto de confusión acústica) se manifiesta en fallas en el recuerdo de series para las listas compuestas por palabras que tienen sonidos similares en comparación con aquéllas que poseen elementos distintos. Con base en el trabajo de Nairne en Kelley (1999), se investigó la medida en la que este efecto clásico de memoria reciente cambia a lo largo del curso de un intervalo de retención. El impacto de la similitud fonológica sobre el desempeño de la memoria a lo largo del tiempo se comparó en tres paradigmas, reconstrucción del orden, recuerdo de series y recuerdo libre. Se presentó a los participantes dos bloques de 15 listas compuestas por 5 palabras monosilábicas, un bloque contenía palabras fonológicamente similares y, el otro, palabras fonológicamente distintas. El recuerdo ocurrió después de un intervalo de retención de 2, 8 ó 24 segundos lleno de una tarea digital de sombreado. Los resultados confirmaron y extendieron los de Nairne en Kelley. En las tareas de reconstrucción del orden y en la recuerdo de series, se observó un efecto clásico de similitud fonológica para el intervalo de retención de 2 segundos (es decir, disminución de la ejecución con listas similares). Este efecto desapareció después de un breve periodo de sombreado digital (es decir, un retraso de 8 segundos) y se observó un efecto benéfico de similitud para el intervalo de retención de 24 segundos. En la tarea de recuerdo libre, la similitud fonológica produjo mejor ejecución independientemente del retraso entre la presentación y el recuerdo. Tales resultados se discuten a la luz del modelo de Nairne (1990a) y confirman el papel que desempeñan los procesos de reactivo específico e interreactivo en la reconstrucción del orden, y en el recuerdo de series y libre.     

Compelling untruths: The effect of retention interval on content borrowing and vivid false memories

False memories are sometimes vivid and detailed. We proposed that the details that come to be associated with false memories may be produced by a process called content borrowing. In content borrowing, details from presented items are erroneously borrowed to corroborate the occurrence of the false memory item. In the present research we used think-out-loud protocols at both study and test to provide evidence for content borrowing in the DRM paradigm. We also demonstrated that content borrowing was more common after a 2-week delay, and was more common for critical lures than for missing exemplars.     

The effect of performer gender,performer skill level,and opponent gender on self-confidence in a competitive situation

An equal number of male and female subjects (N=48), ranging in age from 17 to 26, were randomly assigned to compete in three competitive video games against a male or female opponent. All subjects were given bogus feedback that they had lost two out of three video games by a standard margin. Initial performance expectancies, as well as postcompetition expectancies, of all subjects were recorded. Initial performance expectancy scores recorded prior to competition were analyzed in a 2 (subject gender)×2 (opponent gender) analysis of covariance (ANCOVA) design with initial skill level on a preliminary game as the covariate. No significant gender differences in initial expectancy scores were found. A 2 (subject gender)×2 (opponent gender) ANCOVA design was utilized to analyze the postcompetition expectancy scores with initial performance expectancy as the covariate. The analysis revealed no significant differences. These findings did not support Corbin's (1981) data suggesting that females express significantly less self-confidence than males for future performance after competing against and losing to a superior opponent on a video task. Initial performance expectancies in the present study were significantly correlated (p.05) to skill level, indicating that performance expectancies may be more related to skill level than to gender. Thus, a realistic perception about one's initial skill level on a particular task may be the most salient determinant of performance expectancies.     

Apparent reversal frequencies in squares and trapezia: the effect of invariant and variant information

Three studies of apparent reversals (ARs) in rotating rectangular and trapezoid arrays are reported, together with a mathematical analysis. Study 1 explores the effect of different degrees of outline suppression on the frequency and distribution of ARs in squares and trapezia. Study 2 examines how modifications in both types of array reduce AR frequency, demonstrates a manipulation whereby ARs in rotating squares are eliminated, and suggests that ARs in squares and trapezia are of different origins. In the mathematical analysis, an invariant characteristic of the transformations of rotating rectangles is reported, and from this a numerical index is developed that expresses the extent to which a rotating trapezium may appear to pause just before each point of oscillation. In study 3 it is shown that this measure is a better predictor of AR frequencies than the heuristic proposed by Braunstein.