Biomedical subjects

Kim-Phuong L Vu

Publications and source records attributed to Kim-Phuong L Vu.

At least 19 recordsLinked to original sources

PubMed2007

Transfer of noncorresponding spatial associations to the auditory Simon task.

Four experiments examined transfer of noncorresponding spatial stimulus-response associations to an auditory Simon task for which stimulus location was irrelevant. Experiment 1 established that, for a horizontal auditory Simon task, transfer of spatial associations occurs after 300 trials of practice with an incompatible mapping of auditory stimuli to keypress responses. Experiments 2-4 examined transfer effects within the auditory modality when the stimuli and responses were varied along vertical and horizontal dimensions. Transfer occurred when the stimuli and responses were arrayed along the same dimension in practice and transfer but not when they were arrayed along orthogonal dimensions. These findings indicate that prior task-defined associations have less influence on the auditory Simon effect than on the visual Simon effect, possibly because of the stronger tendency for an auditory stimulus to activate its corresponding response.

Association↗

PubMed2006

Effects of displacement magnitude and direction of auditory cues on auditory spatial facilitation of visual search.

OBJECTIVE: The objective of this study is to examine the effects of cue error on auditory spatial facilitation (ASF) of visual search. BACKGROUND: ASF is the reduction in time needed to locate and identify a visual target when an auditory cue is presented at the location of the target. Although ASF has been shown to occur when the auditory cue coincides with the target location, it is important to determine whether facilitatory effects are also evident when the cue is displaced. METHOD: Participants performed a visual search task in the presence of an auditory cue that was presented at the center of the screen (uninformative), at the location of the target (accurate), or displaced up to 12 degrees from the target horizontally or vertically. RESULTS: Generally, displaced auditory cues reduced search times as compared with a condition in which the cue was uninformative. When the displacement was always along a single spatial dimension, the cue was as effective as a coincident cue if it was within the local visual area. However, when the dimension along which the cue was displaced varied randomly, the cue did not necessarily reduce search time and hurt performance when the visual search task was difficult. CONCLUSION: Designers of virtual audio displays should be aware that auditory cue accuracy will be affected by the difficulty of the visual task and the operators' knowledge of cue precision and reliability. APPLICATION: Findings from this study can be applied to the design of multimodal interfaces and augmented or virtual environments.

California↗

PubMed2006

A deficit in older adults' effortful selection of cued responses.

J. J. Adam et al. (1998) provided evidence for an "age-related deficit in preparing 2 fingers on 2 hands, but not on 1 hand" (p. 870). Instead of having an anatomical basis, the deficit could result from the effortful processing required for individuals to select cued subsets of responses that do not coincide with left and right subgroups. The deficit also could involve either the ultimate benefit that can be attained or the time required to attain that benefit. The authors report 3 experiments (Ns = 40, 48, and 32 participants, respectively) in which they tested those distinctions by using an overlapped hand placement (participants alternated the index and middle fingers of the hands), a normal hand placement, and longer precuing intervals than were used in previous studies. The older adults were able to achieve the full precuing benefit shown by younger adults but required longer to achieve the maximal benefit for most pairs of responses. The deficit did not depend on whether the responses were from different hands, suggesting that it lies primarily in the effortful processing required for those subsets of cued responses that are not selected easily.

Adult↗

PubMed2006

Effects of precuing horizontal and vertical dimensions on right-left prevalence.

When stimuli and responses can be coded along horizontal and vertical dimensions simultaneously, a right-left prevalence effect is often obtained for which the advantage for a compatible mapping is larger on the horizontal dimension than on the vertical dimension. The present study investigated the role of preparatory processes in this right-left prevalence effect using a method in which the relevant dimension was cued at short and long intervals prior to presentation of the target stimulus. In three experiments, the right-left prevalence effect did not vary significantly in magnitude as a function of cue-target interval, suggesting that the effect is due primarily to relative salience of the horizontal and vertical codes, as determined by the task structure, and not to a greater ease of attending to the horizontal dimension.

Cues↗

PubMed2006

Spatial coding in two dimensions.

There has been growing interest in exploring human performance for situations in which stimuli and/or responses vary along both horizontal and vertical dimensions. Earlier studies indicated that there is a prevalence of the horizontal dimension over the vertical dimension in the spatial codes that are used for response selection. We review evidence about spatial coding for 2-D stimulus-response sets and accounts that have been proposed for explaining how it takes place. Particular attention is devoted to the relative salience account, which provides the most comprehensive explanation of 2-D spatial coding. We also evaluate the influence of speed of spatial code formation, number of reference frames, and learning on subjects' performance in 2-D tasks.

Conditioning, Classical↗

PubMed2005

Emergent perceptual features in the benefit of consistent stimulus-response mappings on dual-task performance.

Duncan (1979) examined all combinations of compatible and incompatible stimulus-response mappings for two spatial three-choice tasks in the psychological refractory period paradigm. Performance was better when the mappings for the tasks were consistent than when they were not, even when both mappings were incompatible. He attributed the benefit for the consistent incompatible mapping to an emergent choice between mappings when they are inconsistent that slows performance. Consistent incompatible mappings also may benefit from emergent perceptual features. The present study examined the role of emergent perceptual and mapping-choice features in two experiments that used pairs of two-choice tasks. Results similar to Duncan's were obtained with visual stimuli mapped to keypresses at short (stimulus onset asynchrony) SOAs. However, the benefit of the consistent incompatible mapping condition over the inconsistent mapping conditions was eliminated at an SOA of 1,000 ms. Furthermore, this benefit was not evident when the stimuli were auditory for Task 1 and visual for Task 2. With two-choice tasks, the benefit for consistent mappings apparently is due primarily to an emergent perceptual feature.

Attention↗

PubMed2005

A Simon effect in pigeons.

Pigeons pecked left versus right keys contingent upon the color presented at 1 of those locations. Spatial-response latencies were shorter when the color appeared at the same location as the required response than at the opposite location. This Simon effect occurred when the stimulus on the alternative key was constant, varied from trial to trial, or changed when the color cue appeared and when the reinforcement probability for correct responses was the same on corresponding as on noncorresponding trials. Humans performing the same task by touching the keys also showed the Simon effect. These findings demonstrate that for pigeons, too, a relevant symbolic cue activates a spatial code that produces faster responses at the location corresponding with the activated code.

Animals↗

PubMed2005

Aging and response selection in spatial choice tasks.

Factors that make response selection more difficult, most notably incompatibility between displays and controls, degrade performance. The cost of incompatibility on performance is often much greater for older than for younger adults. To design products that accommodate decreased response selection capabilities of older adults, designers need to understand the specific ways in which response selection processes change with age. The purpose of the present paper is to review research on age-related changes in stimulus-response compatibility and response precuing effects, the two effects that are most directly linked to basic response selection processes. Several specific aspects of response selection that are particularly harmful for older adults' performance are identified. Potential applications of this research include initial guidelines for minimizing the effects of those aspects when designing for older adults.

Adult↗

PubMed2005

No overall right-left prevalence for horizontal and vertical Simon effects.

The present study confirmed that there is no overall right-left prevalence effect for Simon tasks, in which stimulus location is irrelevant, when (1) the stimulus and response sets vary along both horizontal and vertical dimensions simultaneously, (2) the stimulus set varies along both dimensions, but the response set varies along only one dimension, and (3) the stimuli and responses vary in one of four possible locations and responses are made by a unimanual joystick movement. In all experiments, Simon effects of similar magnitude were evident for both the horizontal and the vertical dimensions. The findings suggest that the right-left prevalence effect observed with two-dimensional location-relevant tasks is not due to stronger overall automatic activation of horizontal codes but to different translation efficiencies in intentional response selection processes.

Attention↗

PubMed2004

The enhanced Simon effect for older adults is reduced when the irrelevant location information is conveyed by an accessory stimulus.

The Simon effect, better performance when irrelevant stimulus location corresponds with the response location than when it does not, typically is larger for older than younger adults. However, Simon and Pouraghabagher [Simon, R. J., & Pouraghabagher, A. R. (1978). The effect of aging on the stages of processing in a choice reaction time task. Journal of Gerontology, 33, 553-561] found no age difference using an accessory-stimulus Simon task in which the relevant dimension was the color of a visual stimulus and the irrelevant dimension the location of a tone. Experiment 1 confirmed that older adults show a larger Simon effect than younger adults for the visual Simon task and that this age-related deficit is reduced or eliminated for the auditory-accessory task. Experiment 2 provided evidence suggesting that a small part of the age-related deficit in the visual Simon task is due to having to code the location of the relevant stimulus, but Experiment 3 showed that the majority of the deficit is due to the relevant and irrelevant information being conveyed by the same stimulus. Reaction-time distribution analyses show similar functions for younger and older adults, suggesting that the time course of activation is similar for both age groups.

Adolescent↗

PubMed2004

Mixing compatible and incompatible mappings: elimination, reduction, and enhancement of spatial compatibility effects.

In two-choice tasks, the compatible mapping of left stimulus to left response and right stimulus to right response typically yields better performance than does the incompatible mapping. Nonetheless, when compatible and incompatible mappings are mixed within a block of trials, the spatial compatibility effect is eliminated. Two experiments evaluated whether the elimination of compatibility effects by mixing compatible and incompatible mappings is a general or specific phenomenon. Left-right physical locations, arrow directions, and location words were mapped to keypress responses in Experiment 1 and vocal responses in Experiment 2. With keypresses, mixing compatible and incompatible mappings eliminated the compatibility effect for physical locations and arrow directions, but enhanced it for words. With vocal responses, mixing significantly reduced the compatibility effect only for words. Overall, the mixing effects suggest that elimination or reduction of compatibility effects occurs primarily when the stimulus-response sets have both conceptual and perceptual similarity. This elimination may be due to suppression of a direct response-selection route, but to account for the full pattern of mixing effects it is also necessary to consider changes in an indirect response-selection route and the temporal activation properties of different stimulus-response sets.

Choice Behavior↗

PubMed2003

A feature-integration account of sequential effects in the Simon task.

Recent studies have shown that the effects of irrelevant spatial stimulus-response (S-R) correspondence (i.e., the Simon effect) occur only after trials in which the stimulus and response locations corresponded. This has been attributed to the gating of irrelevant information or the suppression of an automatic S-R route after experiencing a noncorresponding trial-a challenge to the widespread assumption of direct, intentionally unmediated links between spatial stimulus and response codes. However, trial sequences in a Simon task are likely to produce effects of stimulus- and response-feature integration that may mimic the sequential dependencies of Simon effects. Four experiments confirmed that Simon effects are eliminated if the preceding trial involved a noncorresponding S-R pair. However, this was true even when the preceding response did not depend on the preceding stimulus or if the preceding trial required no response at all. These findings rule out gating/suppression accounts that attribute sequential dependencies to response selection difficulties. Moreover, they are consistent with a feature-integration approach and demonstrate that accounting for the sequential dependencies of Simon effects does not require the assumption of information gating or response suppression.

Adolescent↗

PubMed2003

Naïve and experienced judgments of stimulus-response compatibility: implications for interface design.

Many design guidelines encourage maintaining stimulus-response compatibility whenever possible. Payne found that naïve judgments for different stimulus-response (S-R) mappings were not very accurate, and suggested that designers may not be able to predict whether a particular display-control configuration will lead to better performance than another. Three experiments were conducted to determine whether naïve judgments for two-choice tasks in which stimuli and responses involve left-right spatial information are sensitive to (a) the influence of S-R mode relations and (b) pure versus mixed presentation of compatible and incompatible mappings. Initial performance judgments for these conditions were not very accurate, nor were those for four-choice tasks of the type studied by Payne, but subjects' estimates of performance improved with relatively little experience using the different S-R configurations.

Auditory Perception↗

PubMed2003

Does right-left prevalence occur for the Simon effect?

In four experiments, we investigated whether a right-left prevalence effect occurs for the Simon task, in which stimulus location is irrelevant, when the stimulus and the response sets vary along horizontal and vertical dimensions simultaneously. Simon effects were evident for both dimensions, and they were of similar magnitude, indicating no prevalence effect. Manipulations of the relative salience of the dimensions for the stimulus and the response sets resulted in a larger Simon effect for the more salient dimension than for the less salient one, but there was no overall prevalence effect. The results indicate that manipulations of salience affect the relative magnitudes of automatic response activation for the vertical and the horizontal dimensions but that the right-left prevalence effect is due to a coding bias in intentional response selection processes when stimulus location is relevant.

Attention↗

PubMed2003

Transfer effects of incompatible location-relevant mappings on a subsequent visual or auditory simon task.

Two experiments investigated the influence of practice with an incompatible mapping of left and right stimuli to keypress responses on performance of a subsequent Simon task, for which stimulus location was irrelevant, after a delay of 5 min or 1 week. In Experiment 1, the visual Simon effect was eliminated when the practice modality was auditory and reversed to favor noncorresponding responses when it was visual, and there was no significant effect of delay interval. In Experiment 2, significant auditory Simon effects were obtained that did not vary as a function of practice modality, with delay having only a marginal effect on the magnitude of the Simon effect. The elimination of the visual Simon effect in the transfer session is most likely due to the short-term stimulus-response associations defined for the incompatible spatial mapping remaining active during the transfer session. Because the auditory Simon effect is stronger than the visual one, more practice with the incompatible mapping may be necessary to produce reliable transfer effects for it.

Attention↗

PubMed2002

Influences of different combinations of conceptual, perceptual, and structural similarity on stimulus-response compatibility.

This study evaluated the hypothesis that an increase in set-level stimulus-response compatibility produces facilitation for congruent mappings and interference for incongruent mappings. The degree of set-level compatibility was manipulated by varying combinations of conceptual, perceptual, and structural similarity. Experiment 1 varied perceptual similarity, by combining two stimulus codes (spatial, verbal) with two response modalities (manual, vocal) for orthogonal spatial dimensions, which have structural similarity. The element-level mapping effect did not vary as a function of the code-modality relation, in contrast to findings obtained with parallel spatial dimensions, which also have conceptual similarity. Experiment 2 manipulated combinations of conceptual and perceptual similarity by combining vertical and horizontal stimulus and response orientations, using verbal or spatial stimuli and vocal responses. The element-level mapping effect was larger for parallel than orthogonal orientations, with congruent mappings showing facilitation and incongruent mappings showing interference. The largest effect was facilitation for parallel orientations with the verbal-vocal set, consistent with the view that perceptual similarity contributes to performance primarily when responding with the identity of the stimulus. Our results indicate that conceptual similarity, but not perceptual similarity, produces the facilitation/interference pattern suggestive of automatic activation of the corresponding response regardless of mapping.

Conditioning, Classical↗

PubMed2002

The prevalence effect in two-dimensional stimulus-response compatibility is a function of the relative salience of the dimensions.

When stimulus-response (S-R) sets vary along horizontal and vertical dimensions, a right-left prevalence effect is often obtained in which the horizontal compatibility effect is larger than the vertical compatibility effect. Vu and Proctor (2001) showed that the prevalence effect varies as a function of the dimension made salient by the response configuration. A salient features coding interpretation of this result implies that manipulating the salience of the stimulus display should produce similar results and that S-R translation should be fastest when salient features of the stimulus and the response sets correspond. Experiment 1 manipulated spatial proximity to make the vertical or the horizontal stimulus dimension salient. Neutral displays yielded a typical right-left prevalence effect, and this effect was enhanced by horizontal-salient displays and eliminated by vertical-salient displays. Experiments 2 and 3 showed that the benefit for horizontal (or vertical) compatibility was larger when the salient features of both the stimulus and the response sets emphasized the horizontal (or the vertical) dimension than when only one did. The results support salient features coding as an explanation for the prevalence effect obtained with two-dimensional S-R arrangements.

Conditioning, Classical↗

PubMed2002

Mixing location-irrelevant and location-relevant trials: influence of stimulus mode on spatial compatibility effects.

The performance advantage for spatially compatible mappings of physical locations to keypress responses, relative to incompatible mappings, is eliminated when stimulus color, rather than location, is relevant on half of the trials. In Experiment 1, we compared the effects of mixing for different stimulus modes (physical locations, arrow directions, and location words) to determine whether this elimination of the stimulus-response compatibility (SRC) effect would generalize to other stimulus modes. The SRC effect was unaffected when the location information was conveyed by arrows and was amplified when the location information was conveyed by words. In Experiment 2, we used vocal left-right responses instead of keypresses, and the SRC effects for all three stimulus modes were enhanced by mixing. In both experiments, for all stimulus modes, mixing reduced or reversed correspondence effects for trials on which the location information was irrelevant when the mapping for those trials on which it was relevant was incompatible. These findings suggest that when trial types are mixed, direct activation of the corresponding response, regardless of mapping, does not occur for physical locations mapped to keypresses. However, such activation does occur when stimuli or responses are verbal, apparently because performance is mediated in part by activation of a verbal name code for the stimulus.

Humans↗