Variable-interval reinforcement schedule value influences responding following REM sleep deprivation

The effects of rapid-eye movement sleep deprivation (REMSD) in rats were studied in relation to variable-interval (VI) reinforcement schedule value. Initially, lever pressing was maintained on a VI 30-s schedule of food pellet delivery. After a baseline was established, rats were repeatedly exposed to 96 hr of REMSD and control conditions of an equivalent duration. Responding decreased following REMSD but not after exposure to control conditions. Lever pressing was then maintained on a VI 15-s schedule of food pellet delivery and exposure to the REMSD and control conditions was repeated. Under this condition following repeated REMSD exposures, rates of lever pressing became similar to baseline responding. A VI 30-s schedule of food pellet delivery was then reinstated and REMSD and control conditions were repeated. Lever pressing following exposure to the REMSD condition decreased for 3 of 4 rats. Results suggest that VI schedule value influences the effects of REMSD on responding.     

Recovery of performance during sleep following sleep deprivation in older normal and insomniac adult males

Groups of 12 normal and insomniac male subjects aged 55 to 71 yr. were sleep deprived for 64 hr. In both groups, the sleep loss was preceded by four baseline sleep nights and followed by four recovery nights. Reaction time, immediate recall, sleepiness, and body temperature were measured at approximately 2300, 0115, 0330, 0530, and 0800 during baseline, deprivation and recovery nights. Significant performance or mood differences were not found between the normal and insomniac males on any measure or at any testing period throughout the study. Performance of both groups declined characteristically during sleep loss while subjective sleepiness increased. As in young adults, degraded performance was restored by 8 hr. of recovery sleep. However, subjective sleepiness did not return to baseline levels until early in the second recovery night. It was concluded that chronic insomnia does not result in group performance deficits similar to those seen after chronic sleep loss; and the restorative function of sleep operates as efficiently in older insomniac subjects (who apparently have reduced need to sleep) as in older normal subjects.     

Response-retrieval and negative priming

The existence of across-notation automatic numerical processing of two-digit (2D) numbers was explored using size comparisons tasks. Participants were Arabic speakers, who use two sets of numerical symbols—Arabic and Indian. They were presented with pairs of 2D numbers in the same or in mixed notations. Responses for a numerical comparison task were affected by decade difference and unit-decade compatibility and global distance in both conditions, extending previous findings with Arabic digits (Nuerk, Weger, & Willmes, 2001). Responses for a physical comparison task were affected by congruency with the numerical size, as indicated by the size congruency effect (SiCE). The SiCE was affected by unit-decade compatibility but not by global distance, thus suggesting that the units and decades digits of the 2D numbers, but not the whole number value were automatically translated into a common representation of magnitude. The presence of similar results for same- and mixed-notation pairs supports the idea of an abstract representation of magnitude.     

Stimulus-feature specific negative priming

We report the results of two experiments that showed that the time needed to respond to a feature of a stimulus increases when that particular feature of that particular stimulus previously had to be ignored. The data of Experiment 2 argue against the hypothesis that the observed stimulus-feature specific negative priming was due to a response conflict instigated by automatic episodic retrieval of prime responses. Experiment 2 also showed that the effects were not caused by difficulties in switching between prime and probe tasks and provided additional evidence for the fact that priming effects were stimulus-feature specific. The present results suggest that the selective inhibition or episodic encoding mechanisms that are assumed to underlie negative priming can operate in a more specific and powerful manner than has been previously assumed.     

Spatial negative priming in bilingualism

Balanced bilinguals have been shown to have an enhanced ability to inhibit distracting information. In this study, we investigated the hypothesis that the bilinguals’ efficiency in inhibitory control can be advantageous in some conditions, but disadvantageous in others—for example, negative priming conditions, in which previously irrelevant information becomes relevant. Data collected in a target-stimulus locating task from 29 early bilingual adults and 29 age-matched monolinguals showed that the bilinguals’ greater inhibition of irrelevant spatial information (i.e., the position of a distractor stimulus) resulted in a smaller effect of the distractor presence (i.e., a smaller difference in error rates in trials with and without distractors) and a larger negative priming effect (i.e., a larger difference between the error rates shown in trials wherein the target position corresponded to the position of the previous-trial distractor and trials wherein the target was presented in a previously vacant position). These findings support the hypothesis of specific nonlinguistic cognitive effects of bilingualism on inhibitory control functions, which are not necessarily reflected in cognitive advantages.     

ERP correlates of auditory negative priming

Negative priming refers to slowed down reactions when the distractor on one trial becomes the target on the next. Following two popular accounts, the effect might be due either to inhibitory processes associated with the frontal cortex, or to an ambiguity in the retrieval of episodic information. We used event-related brain potentials (ERPs) to identify the processing stage primarily associated with negative priming. In an auditory categorization task, reactions in negative priming trials were compared to reactions in a standard control (unrelated primes and probes) and a repetition control (attended prime=ignored probe) condition. Reactions were slower for negative priming than for standard control (Delta32 ms) and repetition control trials (Delta64 ms). The corresponding ERP effect was reflected in an attenuation of a sustained parietal positivity extending from 300 to 600 ms. Because corresponding ERP components were found to be sensitive to stimulus recognition and familiarity, the results may be interpreted to support an episodic retrieval account of negative priming.     

Varieties of positive and negative priming

Numerous recent investigations have focused on a particular relation between the roles a stimulus plays in successive displays: when a stimulus ignored by a subject on one occasion is to be attended on a succeeding occasion, reaction time to that stimulus is slowed relative to a control condition. But this is but one possible case ofnegative priming. There are other ways in which negative priming might occur, and there are several varieties of positive priming as well. All these possibilities were explored in the present experiment.     

Absorbed in sleep: Dissociative absorption as a predictor of sleepiness following sleep deprivation in two high-functioning samples

In recent years, a labile sleep-wake cycle has been implicated as a cause for dissociative experiences, and studies show that dissociation is elevated following sleep deprivation. Dissociative individuals may find it harder to regulate sleepiness in the face of sleep disruption. Although there is significant variability in reactions to sleep deprivation, research on trait predictors is scarce. The present study examined the ability of trait dissociation to prospectively predict sleepiness following sleep loss and recovery sleep. Two high-functioning samples, namely, Remotely Piloted Aircraft officers (N = 29) and Air Force jet pilots (N = 57) completed state and trait questionnaires assessing sleep and dissociation before and after full or partial sleep loss. Dissociative absorption was a consistent predictor of an increase in sleepiness following sleep loss and following recovery sleep, controlling for baseline sleepiness levels. We discuss the findings in light of a difficulty to regulate and monitor consciousness states.     

The negative priming effect: Inhibitory priming by ignored objects

A priming paradigm was employed to investigate the processing of an ignored object during selection of an attended object. Two issues were investigated: the level of internal representation achieved for the ignored object, and the subsequent fate of this representation. In Experiment 1 a prime display containing two superimposed objects was briefly presented. One second later a probe display was presented containing an object to be named. If the ignored object in the prime display was the same as the subsequent probe, naming latencies were impaired. This effect is termed negative priming. It suggests that internal representations of the ignored object may become associated with inhibition during selection. Thus, selection of a subsequent probe object requiring these inhibited representations is delayed. Experiment 2 replicated the negative priming effect with a shorter inter-stimulus interval. Experiment 3 examined the priming effects of both the ignored and the selected objects. The effect of both identity repetition and a categorical relationship between prime and probe stimuli were investigated. The data showed that for a stimulus selected from the prime display, naming of the same object in the probe display was facilitated. When the same stimulus was ignored in the prime display, however, naming of it in the probe display was again impaired (negative priming). That negative priming was also demonstrated with categorically related objects suggests that ignored objects achieve categorical levels of representation, and that the inhibition may be at this level.     

The effects of total sleep deprivation on semantic priming: Event-related potential evidence for automatic and controlled processing strategies

There is general consensus that performance on a number of cognitive tasks deteriorates following total sleep deprivation. At times, however, subjects manage to maintain performance. This may be because of an ability to switch cognitive strategies including the exertion of compensatory effort. The present study examines the effects of total sleep deprivation on a semantic word priming task. Word priming is unique because it can be carried out using different strategies involving either automatic, effortless or controlled, effortful processing. Twelve subjects were presented with word pairs, a prime and a target, that were either highly semantically associated (cat…dog), weakly associated (cow…barn) or unassociated (apple…road). In order to increase the probability of the use of controlled processing following normal sleep, the subject’s task was to determine if the target word was semantically related to the prime. Furthermore, the time between the offset of the prime and the onset of the target was relatively long, permitting the use of an effortful, expectancy-predictive strategy. Event-related potentials (ERPs) were recorded from 64 electrode sites. After normal sleep, RTs were faster and accuracy higher to highly associated targets; this performance advantage was also maintained following sleep deprivation. A large negative deflection, the N400, was larger to weakly associated and unassociated targets in both sleep-deprived and normal conditions. The overall N400 was however larger in the normal sleep condition. Moreover, a long-lasting negative slow wave developed between the offset of the prime and the onset of the target. These physiological measures are consistent with the use of an effortful, predictive strategy following normal sleep but an automatic, effortless strategy following total sleep deprivation. A picture priming task was also run. This task benefits less from the use of a predictive strategy. Accordingly, in this task, ERPs following the target did not differ as a function of the amount of sleep.     

Spatial stimulus-response compatibility and negative priming

According to Kornblum's (1992) dimensional overlap model, when an incongruent response to a stimulus is required, automatic activation of the congruent response must first be inhibited. Shiu and Kornblum (1996a) provided evidence for such inhibition in an incongruent symbolic negative priming task. Reaction time was longer when a trial's correct response was the name of the stimulus from the previous trial than when it was not. We report three experiments that test this inhibition hypothesis for spatial stimuli and responses. In Experiment 1, which used a spatial mapping analogous to the symbolic mapping used by Shiu and Kornblum (1996a), a similar negative priming effect was found. However, in Experiments 2 and 3, which used mappings that were conducive to simple transformational rules, a positive priming effect was obtained. The results suggest that inhibition in response selection may depend on the complexity of the relations between the stimuli and responses.     

On finding negative priming from distractors

Negative priming from distractors has attracted considerable interest because it appears to reveal a fundamental mechanism of selective attention. Recently, the phenomenon has become muddled because it can be explained in far too many ways. This may partly be because the empirical foundation for the phenomenon has been handicapped by an overreliance on a simplistic comparison of a single experimental condition with control. A sounder approach requires that we collect data that can rule out alternatives to the hypothesis we might favor or test. Regardless of the paradigm used, we propose collecting data from a much fuller set of conditions than is typical. Despite the variety of underlying explanations, we show that the various theories that attribute negative priming to ignoring the distractor predict a common pattern of results across the full set of related conditions. Theories, such as inhibition of return, that do not attribute the cost in performance to ignoring the distractor do not predict this pattern.     

Dissociative prime-probe contextual similarity effects on negative priming and repetition priming: a challenge to episodic retrieval as a unified account of negative priming

This study examined the dependence of repetition priming (RP) and negative priming (NP) as a function of prime-probe contextual similarity in a paradigm in which participants were required to respond to a letter flanked by incompatible distractor letters (e.g., ABA). Experiment 1 used prime and probe displays containing a pair of "+" symbols that were presented horizontally or vertically. Experiments 2 and 3 manipulated whether the letter triplets contained the "!" symbol. In all experiments, regardless of whether the RP trials were intermixed with the NP trials (Experiment 2) or not (Experiment 3), RP was stronger in the prime-probe similar conditions than in the prime-probe dissimilar conditions, but NP was independent of prime-probe contextual similarity. These findings suggest that NP is not necessarily stronger in conditions in which episodic retrieval of the prime is more likely.     

Negative priming with masked distractor-only prime trials: awareness moderates negative priming

The literature yields inconsistent evidence for negative priming (NP) following masked distractor-only prime trials. We contrast two different hypotheses on the inconsistent findings: one - which is most compatible with the temporal discrimination theory - that relates the sign of priming effects to the absence vs. presence of prime awareness and one -which is most compatible with the inhibition and episodic retrieval accounts - that relates the sign of priming effects to the prime event being categorized as a to-be-attended vs. to-be-ignored event. In two experiments, it turned out that participants' awareness of the masked stimuli caused the different results (with participants being not aware of the primes showing NP), whereas the factor prime color = probe target color vs. prime color = probe distractor color (i.e., the prime contains the to-be-attended vs. the to-be-ignored signal) did not moderate NP. These findings are discussed with regard to theories of negative priming and the debate on conscious vs. unconscious perception.     

Relevant distractors do not cause negative priming

Highly relevant stimuli (such as one’s own name) can capture attention in situations in which one can only partially attend to the environment (e.g., the classic “cocktail party” phenomenon, introduced by Moray, 1959). The present study extends previous findings on selection tasks demonstrating these intrusions of relevant stimuli. Not only can highly relevant stimuli be detected more easily, but attempts to deliberately ignore them will also be hampered, so subsequent reactions to such stimuli will not be slowed. In the experiment, participants (N = 32) ignored the first names of other participants without problems, and they showed slowed reactions to such names that they had ignored shortly before (negative priming task). In contrast, no slowing was observed for participants’ own names when those names had just previously been used as distractors.     

Normal auditory negative priming in schizophrenic patients

Performance of 28 schizophrenic patients and 28 matched controls was compared in an auditory priming task. A large auditory negative priming effect was obtained for the patients as well as for the control group, and the size of the negative priming effect was approximately the same for both groups. Under the same conditions, positive or repetition priming for the patients was enhanced compared to that of the control group. The present findings from an auditory priming task are consistent with a growing body of evidence from the visual domain showing normal rather than reduced or eliminated negative priming in schizophrenic patients.     

Mask-induced priming and the negative compatibility effect

Under certain conditions, masked primes have produced counter-intuitive negative compatibility effects (NCE), such that RT is increased, not decreased, when the target is similar to the prime. This NCE has been interpreted as an index of automatic motor inhibition, triggered to suppress the partial motor activation caused by the prime. An alternative explanation is that perceptual interactions between prime and mask produce positive priming in the opposite direction to the prime, explaining the NCE without postulating inhibition. Here the potential role of this "mask-induced priming" was investigated in two experiments, using masks composed of random lines. Experiment 1 compared masks that included features of the primes and targets with masks that did not. The former should create more mask-induced priming, but the NCE did not differ between masks. Experiment 2 employed masks that contained features of either one target or the other, but not both. These asymmetric masks produced significant mask-induced priming, but it was insufficient in size to account for the prime-related NCE. Thus mask composition can contribute to NCEs, but when random line masks are employed, the major source of the NCE seems to be motor-inhibition.     

Normal auditory negative priming in schizophrenic patients

Performance of 28 schizophrenic patients and 28 matched controls was compared in an auditory priming task. A large auditory negative priming effect was obtained for the patients as well as for the control group, and the size of the negative priming effect was approximately the same for both groups. Under the same conditions, positive or repetition priming for the patients was enhanced compared to that of the control group. The present findings from an auditory priming task are consistent with a growing body of evidence from the visual domain showing normal rather than reduced or eliminated negative priming in schizophrenic patients.