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Z Dienes

Publications and source records attributed to Z Dienes.

16 recordsLinked to original sources
PubMed2006

The effect of alcohol and repetition at encoding on implicit and explicit false memories.

RATIONALE: Alcohol impairs explicit memory, whilst leaving implicit memory relatively intact. Less is known about its effects on false memories. AIM: The present study examines the effects of alcohol on explicit and implicit false memories using study list repetition as a tool for modulating learning at encoding. METHODS: Thirty-two participants were given either an alcohol (0.6 g/kg) or placebo beverage before undergoing an encoding phase consisting of 10 lists of nine associated words (veridical items). Each list was associated to a word, which was not presented at encoding (semantically associated non-studied lure; critical item), serving as the measure for false memory. Half of the lists were presented once, and half were repeated three times. The next day, participants underwent an implicit (stem completion and post hoc awareness measurements), and an explicit (free recall) task. RESULTS: Alcohol decreased veridical and false explicit memory for singularly presented lists compared to placebo; no group difference existed for repeated lists. Implicit veridical memory was not affected by alcohol. Awareness memory measures demonstrated in placebo participants an increased ability with repetition in rejecting false memories. The reverse was found in intoxicated participants who with repetition accepted more false memories. CONCLUSION: Alcohol appears to decrease semantic activation leading to a decline in false memories. Increased learning with repetition, which increases the rejection of false memories under placebo, is reversed under alcohol leading to a decrease in rejection of false memories. The latter effect of alcohol may be due to its ability to impair monitoring processes established at encoding.

Adolescent↗
PubMed2001

State-dependent effects of alcohol on recollective experience, familiarity and awareness of memories.

RATIONALE: Explicit memory (EM) is the memory for events which occurs with full awareness of where and how the recalled events took place, whereas implicit memory (IM) is the memory which is unfolded without any awareness of these events and usually becomes apparent when performance is facilitated by its presence. These two types of memory can be understood as different systems. Findings attempting to differentiate between the two systems in normal subjects have been controversial, with some researchers arguing that there is a single memory system and only the match in processes used during learning and later at retrieval can be important. OBJECTIVES: The present study compared the effects of alcohol (0.8 g/kg) or placebo administered prior to encoding and/or retrieval on measures of explicit and implicit memory in terms of recollective experience and familiarity. METHODS: At encoding subjects studied a list of 80 words presented in pairs. At retrieval, participants first carried out an implicit stem completion task, followed by an explicitly cued recall task (stem completion) which measured IM and EM respectively. After stem completion participants were required to indicate whether the items from the studied list were consciously recollected ("remember" response) or was known for a fact that were presented in the studied list ("know" response). In the IM task completed items from the studied list but not recognised by the subjects as such indicated memory without awareness. Studied items were of high and low associations. Forty-eight participants were tested in one of four drug conditions: alcohol-alcohol, placebo-placebo, placebo-alcohol, alcohol-placebo. RESULTS: In the implicit stem completion task, alcohol did not affect overall correct completion rates. However, participants who received alcohol prior to encoding reported lower awareness of correctly completed study items. In the cued recall task, alcohol also did not affect overall performance. However, participants in the same drug-state conditions (SS) reported greater recollection than familiarity with study material, whereas participants who encoded and retrieved material in different drug-state conditions (DS) reported recollection and familiarity to the same extent. In addition, DS participants showed more familiarity with study material compared to SS participants. Direct comparisons between IM and EM tasks demonstrated that alcohol at retrieval decreased the cued recall of items from high associations compared to placebo, but did not have any effect on implicit stem completion. CONCLUSIONS: In summary, these results demonstrate a dissociation of alcohol effects on measures of EM and IM. Alcohol administered prior to encoding reduced awareness of implicitly retrieved material, but did not impair IM per se, confirming previous findings with alcohol. In addition, the data provided new evidence for state-dependent retrieval effects on EM but not IM. It was also shown that for explicitly retrieved items, recollective experience benefits from same drug state, whereas familiarity benefits from different drug state between encoding and retrieval.

Adolescent↗
PubMed2001

Toward a unified fielder theory: what we do not yet know about how people run to catch a ball.

Linear optic trajectory theory claims that people catch balls by running in a direction that keeps an optic trajectory of the ball linear. The authors show a range of ball trajectories for which departures of the optic trajectory from linearity do not predict which direction people will run, and the direction they choose does not correct these departures. Data from a wide range of ball trajectories show that people run so that the angle of elevation of gaze to the ball increases at a decreasing rate. But it is not yet known why people choose the particular path they do from the many that would achieve this.

Adolescent↗
PubMed2000

The effects of cigarette smoking on negative priming.

Nicotine administration has been found to enhance performance on tasks of selective attention. It has been proposed that efficient attentional filtering depends on the successful inhibition of distracting information. In the work reported here, a negative priming paradigm was adopted to test whether smoking enhanced the inhibition of irrelevant information. Thirty-six minimally deprived smokers, half of whom smoked and half of whom sham smoked, completed the negative priming task. A significantly larger negative priming effect was found in participants who had smoked in comparison with those who sham smoked. These results support the hypothesis that nicotine enhances the inhibition of distracting information and thus suggest a possible mechanism by which smoking may enhance selective attention.

Adolescent↗
PubMed1999

A theory of implicit and explicit knowledge.

The implicit-explicit distinction is applied to knowledge representations. Knowledge is taken to be an attitude towards a proposition which is true. The proposition itself predicates a property to some entity. A number of ways in which knowledge can be implicit or explicit emerge. If a higher aspect is known explicitly then each lower one must also be known explicitly. This partial hierarchy reduces the number of ways in which knowledge can be explicit. In the most important type of implicit knowledge, representations merely reflect the property of objects or events without predicating them of any particular entity. The clearest cases of explicit knowledge of a fact are representations of one's own attitude of knowing that fact. These distinctions are discussed in their relationship to similar distinctions such as procedural-declarative, conscious-unconscious, verbalizable-nonverbalizable, direct-indirect tests, and automatic-voluntary control. This is followed by an outline of how these distinctions can be used to integrate and relate the often divergent uses of the implicit-explicit distinction in different research areas. We illustrate this for visual perception, memory, cognitive development, and artificial grammar learning.

Cognition↗
PubMed1998

Incorporation of rhodopsin in laterally structured supported membranes: observation of transducin activation with spatially and time-resolved surface plasmon resonance.

Rhodopsin-transducin coupling was used as an assay to investigate a laterally patterned membrane reconstituted with a receptor and its G protein. It served as a model system to show the feasibility to immobilize G protein-coupled receptors on solid supports and investigate receptor activation and interaction with G proteins by one-dimensional imaging surface plasmon resonance. Supported membranes were formed by the self-assembly of lipids and rhodopsin from detergent solution onto functionalized gold surfaces. They formed micrometer-sized alternating regions of pure fluid phospholipid bilayers separated by bilayers composed of an outer phospholipid leaflet on a gold-attached inner thiolipid. Rhodopsin was found to incorporate preferentially into the phospholipid bilayer regions, whereas transducin was uniformly distributed over the entire outer surface of the supported patterned membrane. The influence of rhodopsin on the dark binding of transducin to lipid membranes was described quantitatively and compared with previously published data. Coupling reactions with transducin resembled closely the native system, indicating that the native functionality of rhodopsin was preserved in the supported membranes. The spatially varying properties of the membranes resulted in a pattern of rhodopsin activity on the surface. This combination of techniques is very promising for the investigation of the lateral diffusion of transducin, can be extended to include signalling proteins downstream of the G protein, and may be applied to functional screening of other G protein-coupled receptors. In the future, it may also serve as a basis for constructing biosensors based on receptor proteins.

Biosensing Techniques↗
PubMed1998

The role of implicit memory in controlling a dynamic system.

The relationship between implicit memory and implicit learning is explored. Dienes and Fahey (1995) showed that learning to control a dynamic system was mediated by a look-up table consisting of previously successful responses to specific situations. The experiment reported in this paper showed that facilitated performance on old situations was independent of the subjects' ability to recognize those situations as old, suggesting that memory was implicit. Further analyses of the Dienes and Fahey data replicated this independence of control performance on recognition. However, unlike the implicit memory revealed on fragment completion tasks, successful performance on the dynamic control tasks was remarkably resilient to modality shifts. The results are discussed in terms of models of implicit learning and the nature of implicit memory.

Adolescent↗
PubMed1997

Reversible oriented surface immobilization of functional proteins on oxide surfaces.

Reversible and oriented immobilization of proteins in a functionally active form on solid surfaces is a prerequisite for the investigation of molecular interactions by surface-sensitive techniques. We demonstrate a method generally applicable for the attachment of proteins to oxide surfaces. A nitrilotriacetic acid group serving as a chelator for transition metal ions was covalently bound to the surface via silane chemistry. Reversible binding of the green fluorescent protein, modified with a hexahistidine extension, was monitored in situ using total internal reflection fluorescence. The association constant and kinetic parameters of the binding process were determined. The reversible, directed immobilization of proteins on surfaces as described here opens new ways for structural investigation of proteins and receptor-ligand interactions.

Chelating Agents↗
PubMed1993

How to catch a cricket ball.

A cricket or baseball fielder can run so as to arrive at just the right place at just the right time to catch a ball. It is shown that if the fielder runs so that d2(tan alpha)/dt2 = 0, where alpha is the angle of elevation of gaze from fielder to ball, then the ball will generally be intercepted before it hits the ground. This is true whatever the aerodynamic drag experienced by the ball. The only exception is if the ball is not approaching the fielder before he starts to run.

Attention↗
PubMed1992

Levels of processing for visual stimuli in an "extinguished" field.

Volpe et al. (Nature 282, 722, 1979 [19]) described an experimental study of four patients with parietal tumours who were able to judge whether two simultaneous stimuli were identical or different, even when they were unable to name the stimulus contralateral to their brain injury. We report the case of another patient, E.M., in whom we have investigated this phenomenon further. E.M. had undergone a right temporal lobectomy to prevent recurrent seizures. She could correctly name photographs of objects presented in isolation to either the left or right visual field, at 150 msec exposure (although she was impaired for single objects on the left at 10 msec exposures). She was able to judge correctly whether two simultaneous objects on the left and right had the same or different names, even though she was often unable to name the object on the left. These judgements remained above chance when same-name pairs of stimuli showed the same object but seen from two different viewpoints, or even when they showed visually dissimilar exemplars of the same name category. This implies that the patient based her same-different judgements on categorical information about the pair of objects, even though she was often unable to name the contralateral object.

Adult↗
PubMed1992

Are direction and speed coded independently by the visual system? Evidence from visual search.

Three visual search experiments examined whether motion is coded as two separate features, speed and direction. Increasing the heterogeneity of the directions in which stimuli moved disrupted detection of a target defined by speed (fast among medium and slow nontargets), suggesting that speed is coded integrally with direction. However, heterogeneity in speed did not disrupt detection of a target moving in a particular direction among nontargets with different directions. This suggests that direction is coded independently of speed. The apparent paradox raised by these contrasting conclusions is consistent with neurophysiological and computational models of motion-detection, which suggest that low-levels of the visual system contain direction-detectors insensitive to speed, while speed is coded at higher levels by detectors which are also sensitive to direction. Evidence consistent with the existence of the latter conjunction detectors was obtained in a final experiment which found search for a conjunction of speed and direction to be parallel.

Adult↗
PubMed1992

Motion coherence and conjunction search: implications for guided search theory.

Feature integration theory has recently been revised with two proposals that visual conjunction search can be parallel under some circumstances--either because items with nontarget features are inhibited, or because items with target features are excited. We examined whether excitatory or inhibitory guidance controlled conjunction search for an X oscillating in one direction among Os oscillating in that direction and Xs oscillating in another. Search was affected by whether items oscillated in phase with each other, and it was exceptionally difficult when items with target motion moved out of phase with each other and items with nontarget motion moved out of phase. The results suggest that conjunction search can be guided both by excitation of target features and by inhibition of nontarget features.

Adolescent↗
PubMed1991

Filtering by movement in visual search.

Search for a target defined by a conjunction of movement and form (e.g., an X moving up in a display of intermingled Os moving up and stationary Xs) is parallel. This result is also found if (a) the moving Os and target X move in unpredictable directions so that the moving stimuli do not form a clear perceptual group or (b) the nontarget Xs also move but in a known, different direction from the Os and target X. In contrast, search is slow and serial if the target may be unpredictably among either moving or stationary stimuli. These results suggest that a component of the visual system operates as a movement filter that can direct attention to stimuli with a common movement characteristic. The filtering cue can be moving (vs. stationary), or movement in 1 particular direction. The results do not support the view that attention can only be directed to groups defined by common fate.

Adult↗
PubMed1991

Implicit and explicit knowledge bases in artificial grammar learning.

Two experiments examined the claim for distinct implicit and explicit learning modes in the artificial grammar-learning task (Reber, 1967, 1989). Subjects initially attempted to memorize strings of letters generated by a finite-state grammar and then classified new grammatical and nongrammatical strings. Experiment 1 showed that subjects' assessment of isolated parts of strings was sufficient to account for their classification performance but that the rules elicited in free report were not sufficient. Experiment 2 showed that performing a concurrent random number generation task under different priorities interfered with free report and classification performance equally. Furthermore, giving different groups of subjects incidental or intentional learning instructions did not affect classification or free report.

Adult↗