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Biomedical subjects

H E Egeth

Publications and source records attributed to H E Egeth.

At least 19 recordsLinked to original sources
PubMed2001

Using pictographs to enhance recall of spoken medical instructions II.

The first study in this series [Houts PS, Bachrach R, Witmer JT, Tringali CA, Bucher JA, Localio RA. Patient Educ. Couns. 1998;35:83-8] found that recall of spoken medical instructions averaged 14% but that, when pictographs (drawings representing the instructions) accompanied the spoken instructions and were present during recall, 85% of medical instructions were remembered correctly. Those findings suggested that spoken instructions plus pictographs may be a way to give people with low literacy skills access to medical information that is normally available only in written form. However, there were three important limitations to that study: (1) the subjects were literate and perhaps literate people remember pictograph meanings better than people with low literacy skills; (2) only short term recall was tested and, for medical information to be useful clinically, it must be remembered for significant periods of time and (3) a maximum of 50 instructions were shown in pictographs, whereas managing complex illnesses may require remembering several hundred instructions. This study addresses those limitations by investigating 4-week recall of 236 medical instructions accompanied by pictographs by people with low literacy skills. Subjects were 21 adult clients of an inner city job training program who had less than fifth grade reading skills. Results showed 85% mean correct recall of pictograph meanings immediately after training (range from 63 to 99%) and 71% after 4 weeks (range from 33 to 94%). These results indicate that people with low literacy skills can, with the help of pictographs, recall large amounts of medical information for significant periods of time. The impact of pictographs on symptom management and patient quality of life remains to be studied.

Adolescent↗
PubMed1999

On the distinction between visual salience and stimulus-driven attentional capture.

It is often assumed that the efficient detection of salient visual objects in search reflects stimulus-driven attentional capture. Evidence for this assumption, however, comes from tasks in which the salient object is task relevant and therefore may elicit a deliberate deployment of attention. In 9 experiments, participants searched for a nonsalient target (vertical among tilted bars). In each display, 1 bar was highly salient in a different dimension (e.g., color or motion). When the target and salient elements coincided only rarely, reducing the incentive to attend deliberately to the salient stimuli, response times depended little on whether the target was salient, although some interesting exceptions were observed. It is concluded that efficient selection of an element in visual search does not constitute evidence that the element captures attention in a purely stimulus-driven fashion.

Adolescent↗
PubMed1998

Goal-directed and stimulus-driven attention in cross-dimensional texture segregation.

Goal-directed and stimulus-driven control of attention was examined in a visual texture segregation task. Recent published reports have debated the existence and efficiency of goal-directed guidance of attention. Some of this research has focused on the apparent stimulus-driven attentional priority given to salient distractors, even when they are known to be irrelevant to the task. In the present study, subjects searched a texture array for targets defined along one dimension. These displays also included distractors created by variation in an irrelevant dimension. Targets were of three different overall shapes. On each trial, distractors could be the same shape as the target or one of the other two shapes. In two experiments subjects were informed of the overall shape of the target prior to stimulus presentation. In these experiments, distractors that did not match the overall shape of the target caused less interference than distractors that matched the target's shape. In the third experiment, subjects were not informed of the overall shape of the target. In this experiment all distractors caused roughly equal interference. The results of these experiments demonstrate that if subjects are given information about the overall shape of the target, they are able to use this information to reduce interference from distractors that do not match the overall target shape. While acknowledging some stimulus-driven interference, this illustrates a previously unexplored source of goal-directed guidance that can reduce interfering effects of even salient distractors and argues against purely stimulus-driven control of attention.

Attention↗
PubMed1997

Goal-directed guidance of attention: evidence from conjunctive visual search.

Conjunctive visual search is most difficult when distractor types are in equal proportions and gets easier as the proportions diverge (e.g., E. Zohary & S. Hochstein, 1989). This may reflect restriction of search to the feature shared by the target and the less-frequent distractor. Alternatively, such effects could reflect target salience, which varies with distractor ratio. In 2 experiments, 60 participants searched 64-element displays for a conjunctive target among distractors of 2 types in various proportions. Participants were correctly informed (Experiment 1) or misinformed (Experiment 2) about which distractor type would be less frequent on most trials. In both experiments, the distractor-ratio effect was significantly influenced by the information provided to participants. These findings demonstrate the efficacy of top-down information in guiding attention and show that it can be applied flexibly, weighted toward particular target features.

Attention↗
PubMed1997

Visual attention: control, representation, and time course.

Three central problems in the recent literature on visual attention are reviewed. The first concerns the control of attention by top-down (or goal-directed) and bottom-up (or stimulus-driven) processes. The second concerns the representational basis for visual selection, including how much attention can be said to be location- or object-based. Finally, we consider the time course of attention as it is directed to one stimulus after another.

Attention↗
PubMed1997

Beyond similarity: masking of the target is sufficient to cause the attentional blink.

When subjects are asked to identify a letter target embedded in a rapid serial visual presentation stream, the detection of a subsequent letter probe is briefly impaired. This transient deficit in probe detection, termed the "attentional blink," depends on the type of item that immediately follows the letter target (Raymond, Shapiro, & Arnell, 1995). Two models have been proposed to account for this effect. The interference model of the attentional blink predicts that visual similarity between the probe and item immediately following the target (+1 item) causes the attentional blink, whereas the two-stage model is based on the notion that increased time needed to process the target letter causes the attentional blink. In order to test between these two possibilities, the masking properties of the +1 item and its similarity to the probe were varied. We found the attentional blink when the +1 item acted as a mask of the target, even though the +1 item and the probe were visually dissimilar. This pattern of results supports the two-stage model of the attentional blink.

Adult↗
PubMed1994

Overriding stimulus-driven attentional capture.

Theeuwes (1992) found a distracting effect of irrelevant-dimension singletons in a task involving search for a known target. He argued from this that selectivity is determined solely by stimulus salience; the parallel stage of visual processing cannot provide top-down guidance to the attentive stage sufficient to permit completely selective use of task-relevant information. We argue that in the task used by Theeuwes, subjects may have adopted the strategy of searching for an odd form even though the specific target form was known. In Experiment 1, we replicated Theeuwes's findings. Search for a circle target among diamond nontargets was disrupted by the presence of a diamond nontarget that was uniquely colored. In two subsequent experiments, we discouraged the singleton detection strategy, forcing subjects to search for the target feature. There was no distracting effect of a color singleton in these experiments, even with displays physically identical to those of Experiment 1, demonstrating that top-down selectivity is indeed possible during visual search. We conclude that goal-directed selection of a specific known featural identity may override stimulus-driven capture by salient featural singletons.

Adult↗
PubMed1993

Response time and accuracy revisited: converging support for the interactive race model.

The interactive race model embodies 2 central claims: that divided attention is best described as a race between separately processed codes and that the 2 types of design contingency to which the model is sensitive affect different processing stages. Previous support for the model has come from a series of redundant-target tasks examining reaction time (RT) (J.T. Mordkoff & S. Yantis, 1991). We tested both central claims using near-threshold, accuracy tasks. This approach capitalizes on a known difference between RT and accuracy measures: that (in simple tasks) accuracy is sensitive only to perceptual manipulations, whereas RT is affected by both perceptual and postperceptual factors (J.L. Santee & H.E. Egeth, 1982). The results from 3 experiments provide converging support for the proposed loci of the 2 contingency-sensitive mechanisms within the interactive race model, as well as additional evidence concerning the differential sensitivities of RT and accuracy measures.

Adult↗
PubMed1991

Local processes in preattentive feature detection.

Sagi and Julesz (1987) claimed that for a target to be detected preattentively, it must be within some small critical distance of a nontarget. The independent effects of separation and display size, which were confounded in the Sagi and Julesz experiments, were examined. Experiments 1 and 2 revealed that in tasks requiring search for a color-defined target, target-nontarget separation had no effect on reaction time (RT). Display size, however, was inversely related to RT. Experiment 3 ruled out the possibility that the decreasing function of RT with display size was due to arousal caused by higher display luminance. When nontarget grouping was inhibited, (Exp. 4) it was found that RT no longer decreased with increasing display size. This suggests that nontarget grouping may have been the cause of the improved performance at larger display sizes. Experiments 5 and 6 extended the results to line segments, the stimuli used by Sagi and Julesz.

Adolescent↗
PubMed1990

Detecting conjunctions of color and form in parallel.

Certain theories of visual attention assume that at least one processing stage must be serial when the target of search is defined as the conjunction of two or more separable features. To explain why conjunction-search response times do not always form linearly increasing functions of display size, recent versions of this general model have posited the existence of an early parallel process that guides the serial stage toward display elements that are likely targets. Other models have relaxed the seriality assumption, allowing for a limited number of parallel decisions. In the three experiments reported here, a redundant-target detection task was used with conjunctively defined targets and display sizes of two (Experiment 1), one or two (Experiment 2), and six (Experiment 3). In all three experiments, strong evidence for parallel processing was observed. The implications for models of elementary visual processes are discussed.

Attention↗
PubMed1989

Capacity limitations in visual word processing.

The ability of subjects to process English words in a spatially parallel manner was examined in several redundant-target detection tasks. When redundant targets were identical in a given display, processing limitations were evident in a task that required subjects to make semantic categorizations of words. However, parallel processing of identical redundant target words was exhibited in a lexical decision task that required a structural analysis of letter strings, but not an analysis of word meaning. The difference in performance in the two tasks suggests that the capacity for semantic processing is limited. Analyses designed to examine whether the redundancy gain in Experiment 2 could be attributed to limited capacity processing in conjunction with positional preferences provided evidence against this possibility. In addition, these analyses suggested that the processing times for the redundant targets in Experiment 2 might be positively correlated. In the third and fourth experiments, the redundant-target displays contained two different words. Processing interference, in the form of a redundancy loss, was evident in the lexical decision task, but not in the semantic categorization task, confirming a difference in the mode of processing between the two tasks. The results provide evidence against the unlimited-capacity, parallel processing hypothesis of late selection theories of attention.

Adult↗
PubMed1988

Mental curve tracing with elementary stimuli.

It has been proposed that certain spatial relations are determined by an operation, or "visual routine," that can trace along a boundary (Ullman, 1984). This proposal was supported by Jolicoeur, Ullman, and Mackay's (1986) finding that the time required to determine if two Xs are on the same curve increased monotonically with the separation of the Xs along that curve. In the present study the generality of the curve tracing hypothesis was explored across four experiments by using elementary stimuli that eliminated interweaving curves, displaced the fixation point away from the curves and target Xs, and provided a simple alternative to curve tracing--namely, determining whether or not the Xs fell on the same side of the figure. Stimuli consisted of two curves (150 degrees arcs) and two Xs, and each stimulus was presented for 150 ms. In Experiments 1 and 2, subjects were instructed to decide as quickly as possible if the two Xs fell on the same curve or on different curves. Even for these elementary stimuli, mean reaction time (RT) for same trials increased monotonically with the distance separating the Xs. Mean RT for different trials, however, decreased with the distance separating the Xs. In Experiments 3 and 4 alternatives to curve tracing were tested. For same trials the evidence strongly favored curve tracing. However, different trials were apparently solved on the basis of judgmental processes presumably operating in parallel with curve tracing. Curve tracing rates fluctuated across experiments and seemed to be partially governed by the width of the "pathway" provided for the trace.

Female↗
PubMed1984

Searching for conjunctively defined targets.

It has recently been proposed that in searching for a target defined as a conjunction of two or more separable features, attention must be paid serially to each stimulus in a display. Support for this comes from studies in which subjects searched for a target that shared a single feature with each of two different kinds of distractor items (e.g., a red O in a field of black Os and red Ns). Reaction time increased linearly with display size. We argue that this design may obscure evidence of selectivity in search. In an experiment in which the numbers of the two distractors were unconfounded, we find evidence that subjects can search through specified subsets of stimuli. For example, subjects told to search through just the Os to find the red O target do so without searching through Ns. Implications of selective search are discussed.

Adult↗
PubMed1984

Is meaning implicated in illusory conjunctions?

According to feature-integration theory, when attention is diverted from a display, features from different objects in that display may be wrongly recombined, giving rise to "illusory conjunctions" (Treisman & Schmidt, 1982). Two experiments are reported that examine the nature of these illusory conjunctions. In displays that contain color names and adjectives printed in colored ink, subjects made two kinds of interesting and previously unreported errors. Consider, for example, a display that included the word BROWN in red ink and the word HEAVY in green ink. Subjects would sometimes incorrectly report that the word RED or the ink color brown had appeared in the display (e.g., RED in green ink or HEAVY in brown ink). It appears that subjects extract semantic representations from input and are sometimes confused about whether a particular representation has been extracted from a word or a color patch. Contrary to feature-integration theory, these findings suggest that illusory conjunctions may occur with high-level codes as well as with perceptual features.

Color Perception↗
PubMed1982

Do reaction time and accuracy measure the same aspects of letter recognition?

Two experiments indicate that reaction time and accuracy are not always equivalent measures of the underlying processes involved in the recognition of visually presented letters. In conjunction with the results of previous work, our research suggests the following generalizations: (a) Under data-limited viewing conditions (the short exposure durations of the typical tachistoscopic task), response accuracy is sensitive to early perceptual interference between target and noise items, whereas reaction time is more sensitive to later processes involved in response interference. (b) Under resource-limited viewing conditions (the long exposure durations of the typical reaction time task), both accuracy and reaction time appear to be sensitive to processes occurring in the later rather than the earlier stages of processing. Since the two dependent measures do not always reflect the same perceptual processes, we suggest that the convergence of reaction time and accuracy within the context of a specific information processing model should be demonstrated empirically rather than assumed a priori.

Attention↗