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At least 937 records · Page 52Linked to original sources
PubMed2000

Location cue validity affects inhibition of return of visual processing.

Inhibition-of-return is the process by which visual search for an object positioned among others is biased toward novel rather than previously inspected items. It is thought to occur automatically and to increase search efficiency. We examined this phenomenon by studying the facilitative and inhibitory effects of location cueing on target-detection response times in a search task. The results indicated that facilitation was a reflexive consequence of cueing whereas inhibition appeared to depend on cue informativeness. More specifically, the inhibition-of-return effect occurred only when the cue provided no information about the impending target's location. We suggest that the results are consistent with the notion of two levels of visual processing. The first involves rapid and reflexive operations that underlie the facilitative effects of location cueing on target detection. The second involves a rapid but goal-driven inhibition procedure that the perceiver can invoke if doing so will enhance visual search performance.

Analysis of Variance↗
PubMed2002

Wiring of the brain by a range of guidance cues.

During development of the central nervous system, growth cones navigate along specific pathways, recognize their targets and then form synaptic connections by elaborating terminal arbors. To date, a number of developmental and in vitro studies have characterized the nature of the guidance cues that underlie various types of axonal behavior, from initial outgrowth to synapse formation, including pathway selection, polarized growth, orientated growth, termination and branching. New approaches in molecular biology have identified several types of guidance cues, most of which are likely to act as local cues. Moreover, recent studies have indicated that axonal responsiveness to guidance cues changes dynamically, which appears to be elicited by environmental factors encountered by the navigating growth cones. This article addresses what molecular cues are responsible for guidance mechanisms including axonal responsiveness, focusing on axonal behavior in the developmental stages.

Axons↗
PubMedDate not supplied

The discrimination and durability of an ethanol cue in young and mid-aged female mice.

Young adult (6 months) and mid-aged (12 months) C57BL/6 mice both learned to discriminate ethanol (ETOH, 1.0 g/kg) although criterion performance occurred later for mid-aged mice. ETOH discrimination improved with increasing dose (0.25-1.0 g/kg) and the dose-response function was unaffected by age. The ETOH cue had declined by 40 min postinjection for young mice not unlike a previous report for young rats. In contrast, the ETOH cue remained discriminable at 40 min for mid-aged mice, an effect perhaps due to their slower rate of ETOH metabolism and accountable for the previously reported reduction in ethanol consumption by mid-aged mice. Retention tests and reacquisition training both indicated that the ETOH cue can be retained by both age groups for at least 60 days without discrimination training or food deprivation. The present study suggests that the ethanol discriminative cue in mid-aged mice does not differ from that in young adult mice in potency but is more long lasting, the latter perhaps being related to their reduced ethanol consumption. Of significance from a therapeutic perspective, is that the ETOH cue remained discriminable for 2 months in both age groups (i.e., approximately 1/12 of their total life span).

Aging↗
PubMed1998

Effect of same- and different-modality spatial cues on auditory and visual target identification.

A target identification paradigm was used to study cross-modal spatial cuing effects on auditory and visual target identification. Each trial consisted of an auditory or visual spatial cue followed by an auditory or visual target. The cue and target could be either of the same modality (within-modality conditions) or of different modalities (between-modalities conditions). In 3 experiments, a larger cue validity effect was apparent on within-modality trials than on between-modalities trials. In addition, the likelihood of identifying a significant cross-modal cuing effect was observed to depend on the predictability of the cue-target relation. These effects are interpreted as evidence (a) of separate auditory and visual spatial attention mechanisms and (b) that target identification may be influenced by spatial cues of another modality but that this effect is primarily dependent on the engagement of endogenous attentional mechanisms.

Analysis of Variance↗
PubMed1997

Attenuating verbal overshadowing through color retrieval cues.

Five experiments showed that interference resulting from verbalizing visual stimuli (verbal overshadowing) can be reduced by reintroducing visual cues present at encoding. Object color and background color were used as cues. Participants learned either easy- or hard-to-name figures and then performed an image rotation task. Before performing the imagery task, participants were re-presented with the color patch associated with each figure. Color re-presentation attenuated the impairment associated with easy-to-name stimuli (Experiment 1) as well as labeled hard-to-name stimuli (Experiment 2). However, background color cues had no effect on imagery performance (Experiment 3). Experiment 4 showed that naming the object colors at encoding makes color retrieval cues ineffective. Finally, Experiment 5 showed that object color cues can help participants to overcome previously exhibited impairment resulting from covert verbalization.

Color Perception↗
PubMed1998

Effect of stage of change on cue reactivity in continuing smokers.

Three classical conditioning models (the conditioned compensatory response, conditioned withdrawal, and conditioned appetitive motivational models) postulate that drug cues evoke physiological and emotional responses associated with motivational states that prompt drug use. There is accumulating evidence to suggest that factors other than classical conditioning can influence emotional and physiological reactivity to drug stimuli. This study tested whether stage of change affects the nature of reactivity to smoking cues among continuing smokers. Precontemplators (smokers not considering quitting) and contemplators (smokers considering quitting in the near future) watched videotapes containing smoking cues. Emotional and physiological responses to the smoking video were contrasted with responses to a neutral videotape. Precontemplators had lower heart rates than did contemplators in response to the smoking videotape. Both contemplators and precontemplators evinced increased positive affect in response to the smoking cue. A comparison sample of nonsmokers did not show any reactivity to the smoking cue. Implications of these findings for conditioning theories of smoking are discussed.

Adult↗
PubMed2003

Cue abstraction and exemplar memory in categorization.

In this article, the authors compare 3 generic models of the cognitive processes in a categorization task. The cue abstraction model implies abstraction in training of explicit cue-criterion relations that are mentally integrated to form a judgment, the lexicographic heuristic uses only the most valid cue, and the exemplar-based model relies on retrieval of exemplars. The results from 2 experiments showed that, in lieu of the lexicographic heuristic, most participants spontaneously integrate cues. In contrast to single-system views, exemplar memory appeared to dominate when the feedback was poor, but when the feedback was rich enough to allow the participants to discern the task structure, it was exploited for abstraction of explicit cue-criterion relations.

Adolescent↗
PubMed1994

Shifts of visual attention to multiple simultaneous location cues.

Single and simultaneous multiple location cues were presented a brief period of time before the onset of targets that observers were required to identify. Single and multiple cueing effects were similar, even when targets were presented at locations "in between" pairs of cues. This implies that pairs of direct stimulus cues are not processed by an attentional focus of variable spatial extent that encompasses both cued locations. If this were the case, then targets presented in between cued locations would fall within such an attentional focus and identification response times should have been reduced. The increase in these response times that actually occurred when a target was presented at uncued locations in between a pair of cued locations suggests that pairs of cued locations are encoded independently by an operation called spatial indexing. A multiple indexing proposal and its role in mediating visual attention shifts initiated by direct stimulus cues is described.

Attention↗
PubMed1995

Neutral location cues and cost/benefit analysis of visual attention shifts.

The effects of location cuing on target responses can be examined by comparing informative and neutral cuing conditions. In particular, the magnitudes of costs of invalid location cuing and of benefits of valid location cuing can be determined by comparing invalid and valid cue responses to location-nonspecific neutral cue responses. Cost/benefit analysis is based on the assumption that neutral baseline measures reflect a general warning effect about the impending target's onset but no other specific target information. The experiments we report were carried out to determine the appropriateness of two baseline measures for cost/benefit analyses of direct (nonsymbolic) location cuing effects. We found that a multiple-cue baseline attenuated the benefits of valid cuing, and that a background-flash baseline arbitrarily attenuated costs or benefits depending on flash intensity. It is proposed that a background flash is the more suitable neutral cue because it is target-location-nonspecific, but that its intensity should be adjusted to elicit a target-onset warning signal of the same magnitude as the location cues with which it will be compared.

Attention↗
PubMed2002

Motility cues in the tumor microenvironment.

It is now increasingly recognized that the microenvironment plays a critical role in the progression of tumors. Perhaps less obvious is the concept that the microenvironment may share responsibility in determining the "malignant" traits of tumor cells, i.e. invasiveness and metastasis. If tumors are tissues, however unbalanced, rather than a collection of "malignant" cells recruiting local resources for the purpose of growth, then it is inevitable that tumor cells will respond to local stimuli. These stimuli include cues for motility and migration, which normally appear in tissues undergoing formation, remodeling or healing. Carcinoma cells are likely to be sensitive to the motility cues that normally regulate epithelial morphogenetic movements such as ingression, delamination, invagination, and tube or sheet migration. "Malignant" tumors, then, can be redefined as those in which these cues arise more frequently or act more effectively. Here, we expand on this view and propose that invasion and metastasis may be the outcome of tumor cell responses to microenvironmental motility cues. Understanding how such motility cues arise and act, both in normal and tumor tissue, should be a high priority in cancer research.

Animals↗
PubMed2002

Public perception of the risk of HIV infection associated with blood donation: the role of contextual cues.

BACKGROUND: Previous surveys have reported that a high proportion of people believe that HIV can be contracted through donating blood. It was hypothesized that this may reflect an artifact of the survey methods used. This study was therefore designed to test the hypothesis that providing contextual cues specific to HIV would cause respondents to express an increased belief that the virus can be contracted by donating blood. STUDY DESIGN AND METHODS: A one-way, between-group design was used to test this hypothesis. Adult subjects (n=168) were randomly assigned to one of three experimental conditions, all three groups receiving information about the small risk of infection from blood transfusion. The variation across the experimental conditions was the example of infection given (i.e., Condition 1=no specific example of infection risk, Condition 2=data on the small risk of contracting hepatitis C through transfusion, Condition 3=data on the low risk of contracting HIV through transfusion). Respondents answered a single question, "Do you think you could catch HIV by giving (donating) blood in the UK?" RESULTS: Logistic regression analysis revealed that respondents in the HIV-cued condition were almost 11 times (OR=10.6) more likely to answer "Yes" to the survey question, as compared with the no-cue condition. There was no significant difference in response between the no-cue and the hepatitis C-cue conditions. CONCLUSION: Providing contextual cues relating to HIV increased the expressed belief that the virus could be contracted through donating blood. To better develop donor recruitment policies, future survey tools should minimize contextual effects.

Adult↗
PubMed1996

Qualitative cues in the discrimination of affine-transformed minimal patterns.

An important factor in judging whether two retinal images arise from the same object viewed from different positions may be the presence of certain properties or cues that are 'qualitative invariants' with respect to the natural transformations, particularly affine transformations, associated with changes in viewpoint. To test whether observers use certain affine qualitative cues such as concavity, convexity, collinearity, and parallelism of the image elements, a 'same-different' discrimination experiment was carried out with planar patterns that were defined by four points either connected by straight line segments (line patterns) or marked by dots (dot patterns). The first three points of each pattern were generated randomly; the fourth point fell on their diagonal bisector. According to the position of that point, the patterns were concave, triangular (three points being collinear), convex, or parallel sided. In a 'same' trial, an affine transformation was applied to one of two identical patterns; in a 'different' trial, the affine transformation was applied after the point lying on the diagonal bisector was perturbed a short, fixed distance along the bisector, inwards for one pattern and outwards for the other. Observers' ability to discriminate 'same' from 'different' pairs of patterns depended strongly on the position of the fourth, displaced, point: performance varied rapidly when the position of the displaced point was such that the patterns were nearly triangular or nearly parallel sided, consistent with observers using the hypothesised qualitative cues. The experimental data were fitted with a simple probabilistic model of discrimination performance that used a combination of these qualitative cues and a single quantitative cue.

Adult↗
PubMed1997

Blur and contrast as pictorial depth cues.

Studies have shown that blur can act as a pictorial cue to depth perception. But blurring a stimulus reduces its contrast, and studies have also shown that contrast can act as a pictorial cue to depth perception. To determine whether blur and contrast have separate influences on depth perception, each variable was independently manipulated in two experiments. Observers reported depth alternations in a simple reversible figure. Both contrast and blur were found to influence depth perception, but blur had its greatest effect at moderate contrasts. When blurred and sharp stimuli were equated on either Michelson or RMS contrast, blur continued to affect depth perception. Hence blur can act as a depth cue independently of contrast. It is speculated that blur is effective as a pictorial cue because of its usual association with other depth cues, particularly in pictures and photographs.

Adult↗
PubMed1988

Collective cues as a basis for nestmate recognition in polygynous leptothoracine ants.

Three alternative hypotheses have been advanced to explain the dynamics of individually produced nestmate-recognition cues in colonies of social insects: (i) that there is no effective transfer of cues among nestmates (individual hypothesis); (ii) that cues are shared reciprocally among nestmates (collective hypothesis); and (iii) that cues derived from the queen are transferred to all colony members and dominate all other cues in nestmate recognition (queen hypothesis). In the present study, a bioassay based on aggression by laboratory colonies toward workers introduced into their nests was used in conjunction with isolation and interspecific-adoption experiments to test these hypotheses for colonies of two closely related, polygynous, and polydomous ant species, Leptothorax ambiguus and Leptothorax longispinosus. The results provide strong evidence for the collective hypothesis. A collective system has long been postulated as one of the primary modes of nestmate discrimination among social insects but to my knowledge has never before been clearly demonstrated.

Journal Article↗
PubMed2002

Synergistic effects of physical and chemical guidance cues on neurite alignment and outgrowth on biodegradable polymer substrates.

This article demonstrates that directional outgrowth of neurites is promoted by applying a combination of physical and chemical cues to biodegradable polymer substrates. Films of poly-D,L-lactic acid and poly(lactide-co-glycolide) were micropatterned to form grooves on substrate surfaces, using novel indirect transfer techniques developed specifically for biodegradable polymers that cannot be micropatterned directly. Laminin was selectively adsorbed in the grooves. Whole and dissociated dorsal root ganglia were seeded on the substrates and neurite outgrowth and alignment along the microgrooves were measured. The microgrooves provide physical guidance, whereas laminin provides chemical cues to the neurons. The groove depth and spacing were found to significantly influence neurite alignment. The presence of laminin was found to promote neurite adhesion and outgrowth along the grooves. Using a combination of optimized physical and chemical cues, excellent spatial control of directional neurite outgrowth, with up to 95% alignment of neurites, was obtained. The synergistic effect of physical and chemical guidance cues was found to be more effective than individual cues in promoting directional outgrowth of neurites.

Animals↗
PubMed2000

Stride length regulation in Parkinson's disease: the use of extrinsic, visual cues.

It has been well documented that marked improvements in the hypokinetic gait pattern of Parkinson's disease patients are possible with the use of appropriate visual cues. This project served to evaluate Parkinson's disease gait performance as well as residual processing capacity while using fixed or gait-regulated visual cues. Three-dimensional kinematic, kinetic and electromyographic gait analysis was carried out on 14 patients and 14 matched controls in baseline conditions and with two types of visual cues: taped step length (SL) markers and an individualized subject-mounted light device (SMLD). A probe reaction time paradigm was invoked to assess residual processing capacity. Ratings of perceived task load were also made using the NASA-Task Load Index. Stride length and gait velocity were reduced in patients in baseline conditions. Both of these parameters increased to control levels with the use of visual cues. These alterations were generally accompanied by modifications of lower limb kinematics and kinetics towards control subjects. Perceived task load was higher in all conditions and was further elevated by the use of the SMLD for both groups. Patients produced larger overall reaction times, although reaction time was not different between baseline and SL marker conditions. Reaction time was increased in both groups when using the SMLD. The overarching finding is that stride length can be regulated in Parkinson's disease using stationary visual cues without increased central processing capacity or perceived effort. This may occur via utilization of visual feedback, reducing the patients' reliance on kinaesthetic feedback for the regulation of movement amplitude.

Aged↗
PubMed2005

Evidence for PTZ-like cues as a function of time following treatment with chlordiazepoxide: implications for understanding tolerance and withdrawal.

The present study used a two-lever, drug-discrimination procedure to train rats to discriminate between the cues associated with 5 mg/kg of the anxiolytic, chlordiazepoxide (CDP) and 15 mg/kg of the anxiogenic, pentylenetetrazol (PTZ), to investigate the relationship between withdrawal and acute tolerance. Training doses of the two drugs were chosen so that rats responded about equally on both levers when tested on saline (SAL). Following acquisition of the discrimination, rats were injected with 10 mg/kg CDP and tested for lever choice at various intervals from 6 h to 192 h. These tests revealed that cues associated with CDP withdrawal lasted approximately three times longer than the cues associated with the drug's primary effects. At the shortest retest interval (6 h) after treatment with 10 mg/kg CDP, rats responded primarily on the CDP lever, followed by a shift to predominant responding on the PTZ lever at the 16 h and 24 h intervals before returning to predrug, baseline levels at the longer intervals (48-192 h). In order to investigate the relationship between tolerance and withdrawal to the cue properties of CDP, CDP dose-response curves were determined 24 h following treatment with SAL or 10 mg/kg CDP. Acute tolerance, as defined by a rightward, parallel shift in the dose-response function, was observed in the rats pretreated with CDP. Furthermore, it was evident that the baseline shift associated with CDP withdrawal, rather than a weaker drug cue, accounted for acute tolerance. The results from this study are relevant to evaluating the role positive and negative reinforcement play in motivating compulsive drug use.

Animals↗
PubMed1999

Increasing confidence in vergence as a cue to distance.

Multiple cues contribute to the visual perception of an object's distance from the observer. The manner in which the nervous system combines these various cues is of considerable interest. Although it is accepted that image cues play a significant role in distance perception, controversy exists regarding the use of kinaesthetic information about the eyes' state of convergence. We used a perturbation technique to explore the contribution of vergence to visually based distance estimates as a function of both fixation distance and the availability of retinal information. Our results show that the nervous system increases the weighting given to vergence as (i) fixation distance becomes closer; and (ii) the available retinal image cues decrease. We also identified the presence of a strong contraction bias when distance cues were studied in isolation, but we argue that such biases do not suggest that vergence provides an ineffectual signal for near-space perception.

Adolescent↗