Prototype abstraction and distinctive feature learning: An application to learning Chinese characters.

Chinese characters with related meanings often have a common symbol included among their components. In an exemplar-prototype and distinctive feature classification system, the multiple-component characters (the exemplars) can be said to have a common component (the prototype) distinctive to the shared concept. A study was conducted with 60 undergraduates who were administered recognition tests with new and old exemplars and prototypes. Results show that the traditional language learning technique of paired-associate training with exemplars of Chinese characters and specific English translations led to the poorest performance of the 3 methods tested. Learning either the English concept for Chinese exemplars (exemplar-category training) or the English concept for only the distinctive feature (prototype training) produced greatly superior performance. Instructions regarding the nature of Chinese characters had no effect on performance. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fractionating the preview benefit in search: Dual-task decomposition of visual marking by timing and modality.

Providing participants with a preview of half the distractors in a visual search task facilitates performance. The present study examined the effects of secondary tasks on the preview benefit in search. Participants had to attend to a visual or an auditory stream of digits that began either (a) at the onset of the preview or (b) after the preview. Secondary tasks that onset with the preview disrupted the preview benefit irrespective of their modality. Only visual secondary tasks disrupted the benefit in the delayed condition. These selective interference effects suggest that the preview benefit can be fractionated into 2 components: an initialization component that involves modality-independent resources and a maintenance component that depends on visual resources. Results are discussed in relation to theoretical accounts of the preview benefit in search. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Decomposing visual search: evidence of multiple item-specific skills

Four experiments demonstrated that visual search can be decomposed into two components: one consisting of skills shared with memory search and the other consisting of skills not shared with memory search. A training-transfer paradigm was used to test for transfer from memory search to visual search and vice versa. When the same targets and distractors were used in training and transfer, visual search practice completely trained memory search, but memory search practice only partially trained visual search. Learning on both the shared and the private components of visual search benefited more from item-specific training than from nonspecific training. The relationship between the components and some theorized models of visual search are discussed, particularly in terms of prioritization learning.     

The role of component function in visual recognition of Chinese characters

M. Taft and X. Zhu (1997) reported that character decision latencies to real Chinese characters containing components that entered into many combinations were faster than decision latencies to characters with components that entered into only a small number of combinations. However, this effect was restricted to components that appeared on the right side of Chinese characters. In written Chinese, phonetic components tend to appear on the right, and semantic components tend to appear on the left. Therefore, in Taft and Zhu's study, there was the possibility of a confound between position (left vs. right) and function (semantic vs. phonetic). Results of the present experiment show combinability effects for components with semantic and with phonetic functions. Counter to the claim by Taft and Zhu that component frequency effects are constrained by position, when component function was considered, character decision latencies varied with component frequency but not reliably with position.     

Response Selection in Visual Search: The Influence of Response Compatibility of Nontargets.

The authors used visual search tasks in which components of the classic flanker task (B. A. Eriksen & C. W. Eriksen, 1974) were introduced. In several experiments the authors obtained evidence of parallel search for a target among distractor elements. Therefore, 2-stage models of visual search predict no effect of the identity of those distractors. However, clear compatibility effects of the distractors were obtained: Responses were faster when the distractors were compatible with the response than when they were incompatible. These results show that even in parallel search tasks identity information is extracted from the distractors. In addition, alternative interpretations of the results in terms of the occasional identification of a distractor before or after the target was identified could be ruled out. The results showed that flat search slopes obtained in visual search experiments provide no benchmark for preattentive processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of Graded Levels of Physical Similarity and Density on Visual Selective Attention in Patients With Alzheimer's Disease.

A multitarget visual cancellation test was administered to patients with Alzheimer's disease (AD) and age-matched healthy controls (HC). Attentional loads--physical similarity (number of features shared by target and distractors; 3 levels) and density (number of items per page; 3 levels)--were varied systematically. As physical similarity increased, both groups slowed their search, but whereas the HC group maintained accuracy, the AD group increased commission errors and tended to miss more targets. Increased density yielded slower search and more target omissions in the AD group. Commission errors are additional indicators of higher order attentional deficits, especially in early disease. The findings suggest that patients with AD may rely increasingly on physical features of stimuli during a search, leading to inefficient bottom-up processing strategies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Preemption effects in visual search: Evidence for low-level grouping.

Experiments are presented showing that visual search for Mueller-Lyer stimuli is based on complete configurations rather than component segments. Segments easily detected in isolation were difficult to detect when embedded in a configuration, indicating preemption by low-level groups. This preemption--which caused stimulus components to become inaccessible to rapid search--was an all-or-nothing effect and so could serve as a powerful test of grouping. It is shown that these effects are unlikely to be due to blurring by simple spatial filters at early visual levels. It is proposed instead that they are due to more sophisticated processes that rapidly bind contour fragments into spatially extended assemblies. These results support the view that rapid visual search cannot access the primitive elements formed at the earliest stages of visual processing; rather, it can access only higher level, more ecologically relevant structures. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual selective attention after severe closed head injury

This study investigated the nature of selective attention deficits after severe closed head injury (CHI). Twenty participants with severe CHI (greater than 1 year postinjury) and 20 matched controls completed search and nonsearch visual selective attention tasks under conditions of low (Experiment 1) and high (Experiment 2) target-distractor similarity. In the search situations, participants searched visual displays that contained 1, 4, or 8 items for the targets. In the nonsearch situations, the location of the targets was visually cued with a peripheral arrow. The results revealed that in both the low and high target-distractor similarity search conditions. CHI participants required a longer time than controls to locate and identify the target. In contrast, in the nonsearch condition, CHI participants were able to successfully ignore irrelevant task information when target-distractor similarity was low. However, when target-distractor similarity was high, CHI participants had more difficulty than controls ignoring the irrelevant information. These results suggest that, in comparison to controls, CHI participants may be at a disadvantage in selective attention situations when visual search is required and when the discriminability between targets and distractors is difficult.     

The nesting of search contexts within natural scenes: Evidence from contextual cuing.

In a contextual cuing paradigm, we examined how memory for the spatial structure of a natural scene guides visual search. Participants searched through arrays of objects that were embedded within depictions of real-world scenes. If a repeated search array was associated with a single scene during study, then array repetition produced significant contextual cuing. However, expression of that learning was dependent on instantiating the original scene in which the learning occurred: Contextual cuing was disrupted when the repeated array was transferred to a different scene. Such scene-specific learning was not absolute, however. Under conditions of high scene variability, repeated search array were learned independently of the scene background. These data suggest that when a consistent environmental structure is available, spatial representations supporting visual search are organized hierarchically, with memory for functional subregions of an environment nested within a representation of the larger scene. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual search performance among persons with schizophrenia as a function of target eccentricity.

The current study investigated one possible mechanism of impaired visual attention among patients with schizophrenia: a reduced visual span. Visual span is the region of the visual field from which one can extract information during a single eye fixation. This study hypothesized that schizophrenia-related visual search impairment is mediated, in part, by a smaller visual span. To test this hypothesis, 23 patients with schizophrenia and 22 healthy controls completed a visual search task where the target was pseudorandomly presented at different distances from the center of the display. Response times were analyzed as a function of search condition (feature vs. conjunctive), display size, and target eccentricity. Consistent with previous reports, patient search times were more adversely affected as the number of search items increased in the conjunctive search condition. It was important however, that patients’ conjunctive search times were also impacted to a greater degree by target eccentricity. Moreover, a significant impairment in patients’ visual search performance was only evident when targets were more eccentric and their performance was more similar to healthy controls when the target was located closer to the center of the search display. These results support the hypothesis that a narrower visual span may underlie impaired visual search performance among patients with schizophrenia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Applying Concept Similarity to the Evaluation of Common Understanding in Multidisciplinary Learning

The success of an architecture, engineering, and construction (AEC) project largely depends on the effective collaboration of project participants. This characteristic of the industry requires that AEC education shall foster multidisciplinary collaboration skills of students. On the other hand, many AEC education programs have started using information and communication technologies (ICTs) to facilitate teaching and learning such as distance learning. One of the challenges in a computer-mediated learning environment arises from the need for computer systems to determine whether a common understanding regarding a certain subject is established among a group of students. To achieve this goal, ICT needs to be able to detect changes in the knowledge structure of students in order to provide better mediation. This paper presents a study on the development of a concept similarity measure that has less computational complexity than graph-based similarity analyses. The similarity measure is intended to determine the similarity of multiple knowledge structures [e.g., concept maps (CMAPs)] of students. The concept similarity measure is developed based on the feature-based method in which propositions associated with a concept are considered as features of the concept. Therefore, the similarity of concepts can be measured by comparing the propositions of the concepts. In addition, since concepts are the key component of a knowledge structure, the common understanding of students can be determined by measuring the similarity of concepts in the knowledge structure of the students. The proposed measure is evaluated by (1) comparing it with the Dice coefficient for analyzing two sets of concepts; (2) analyzing its performance in a generic case of four CMAPs; and (3) applying it to a case using “photovoltaic system” as an example. In this case, results are intuitively obvious so that calculation results can be corroborated by human judgment. Finally, the concept similarity measure is applied to derive the similarity of CMAPs in the case study. Based on the initial evaluations, this study shows that the proposed measure has demonstrated promising features for determining the similarity of multiple knowledge structures or the common understanding of students. However, when the number of knowledge structures increases, concept similarity analyses become more complicated because uncertain situations arise due to ambiguous human perception to propositions that are shared by multiple concepts. Future research is thus needed to understand and clearly define concept similarity in those situations. In addition, other studies are also identified for future research.     

Automatic guidance of visual attention from verbal working memory.

Previous studies have shown that visual attention can be captured by stimuli matching the contents of working memory (WM). Here, the authors assessed the nature of the representation that mediates the guidance of visual attention from WM. Observers were presented with either verbal or visual primes (to hold in memory, Experiment 1; to verbalize, Experiment 2; or merely to attend, Experiment 3) and subsequently were required to search for a target among different distractors, each embedded within a colored shape. In half of the trials, an object in the search array matched the prime, but this object never contained the target. Despite this, search was impaired relative to a neutral baseline in which the prime and search displays did not match. An interesting finding is that verbal primes were effective in generating the effects, and verbalization of visual primes elicited similar effects to those elicited when primes were held in WM. However, the effects were absent when primes were only attended. The data suggest that there is automatic encoding into WM when items are verbalized and that verbal as well as visual WM can guide visual attention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dimensional analysis of motion: VIII. The role of visual discrimination in motion cycles.

To determine the changes that occur in the duration of component movements of a motion cycle when a specific visual discrimination is imposed on part of the cycle, electronic recordings were made of the durations of the component movements of an assembly task. Although conventional time-motion study based on the therblig system calls for the application of the therblig "select" when a choice is required, implying an operation that can be separately timed, "Results of the present study… indicate that the durations of all four components of a cyclic sequential movement pattern are increased significantly by the addition of a specific visual discrimination." The adequacy of the therblig system for handling perceptual components of a task is questioned. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Infant attention and visual preferences: Converging evidence from behavior, event-related potentials, and cortical source localization.

In this study, we had 3 major goals. The 1st goal was to establish a link between behavioral and event-related potential (ERP) measures of infant attention and recognition memory. To assess the distribution of infant visual preferences throughout ERP testing, we designed a new experimental procedure that embeds a behavioral measure (paired comparison trials) in the modified-oddball ERP procedure. The 2nd goal was to measure infant ERPs during the paired comparison trials. Independent component analysis (ICA) was used to identify and to remove eye-movement components from the electroencephalographic data, thus allowing for the analysis of ERP components during paired comparison trials. The 3rd goal was to localize the cortical sources of infant visual preferences. Equivalent current dipole analysis was performed on the ICA components related to experimental events. Infants who demonstrated novelty preferences in paired comparison trials demonstrated greater amplitude Negative central ERP components across tasks than infants who did not demonstrate novelty preferences. Visual preference also interacted with attention and stimulus type. The cortical sources of infant visual preferences were localized to inferior and superior prefrontal cortex and to the anterior cingulate cortex. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Memory for where, but not what, is used during visual search.

Although the role of memory in visual search is debatable, most researchers agree with a limited-capacity model of memory in visual search. The authors demonstrate the role of memory by replicating previous findings showing that visual search is biased away from old items (previously examined items) and toward new items (nonexamined items). Furthermore, the authors examined the type of memory representations used to bias search by changing an item's individuating feature or location during search. Changing the individuating feature of an item did not disrupt normal search biases. However, when the location of an item changed, normal search biases were disrupted. These results suggest that memory used in visual search is based on items' locations rather than their identity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The suppression of reflexive visual and auditory orienting when attention is otherwise engaged.

Two experiments were conducted to examine whether abrupt onsets are capable of reflexively capturing attention when they occur outside the current focus of spatial attention, as would be expected if exogenous orienting operates in a truly automatic fashion. The authors established a highly focused attentional state by means of the central presentation of a stream of visual or auditory characters, which participants sometimes had to monitor. No intramodal reflexive cuing effects were observed in either audition or vision when participants performed either an exogenous visual or auditory orthogonal cuing task together with the central focused attention task. These results suggest that reflexive unimodal orienting is not truly automatic. The fact that cuing effects were eliminated under both unimodal and cross-modal conditions is consistent with the view that auditory and visual reflexive spatial orienting are controlled by a common underlying neural substrate. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the speed of pop-out in feature search.

When something unique is present in a scene, this element may become immediately visible and one has the impression that it pops out from the scene. This phenomenon, known as pop-out in the visual search literature, is thought to produce the fastest search possible, and response times for the detection of the pop-out target do not vary as a function of the number of nontargets. In this study, we challenge this notion and show that the detection of a given visual feature is faster for multiple targets than for a single pop-out target. However, when the task requires a detailed target analysis, the pop-out condition can be faster than the multiple-target condition. Current models of visual search are discussed in light of the findings. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

When visual marking meets the attentional blink: More evidence for top-down, limited-capacity inhibition.

An attentional blink (AB) paradigm was used to investigate the attentional resources necessary for visual marking. The results showed that distractors presented inside the AB cannot easily be ignored despite participants anticipating a future target display. This supports the hypothesis that attentional resources are required for visual marking. In addition, probe dots were better detected on blinked distractors than on successfully ignored distractors, but only when the task required new items to be prioritized. In a final experiment, a stronger negative carry-over effect on search occurred for targets identical to distractors presented outside rather than inside the AB. This suggests that at least part of the inhibitory processes involved in visual marking are nonspatial. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual search asymmetries within color-coded and intensity-coded displays.

Color and intensity coding provide perceptual cues to segregate categories of objects within a visual display, allowing operators to search more efficiently for needed information. Even within a perceptually distinct subset of display elements, however, it may often be useful to prioritize items representing urgent or task-critical information. The design of symbology to produce search asymmetries (Treisman & Souther, 1985) offers a potential technique for doing this, but it is not obvious from existing models of search that an asymmetry observed in the absence of extraneous visual stimuli will persist within a complex color- or intensity-coded display. To address this issue, in the current study we measured the strength of a visual search asymmetry within displays containing color- or intensity-coded extraneous items. The asymmetry persisted strongly in the presence of extraneous items that were drawn in a different color (Experiment 1) or a lower contrast (Experiment 2) than the search-relevant items, with the targets favored by the search asymmetry producing highly efficient search. The asymmetry was attenuated but not eliminated when extraneous items were drawn in a higher contrast than search-relevant items (Experiment 3). Results imply that the coding of symbology to exploit visual search asymmetries can facilitate visual search for high-priority items even within color- or intensity-coded displays. (PsycINFO Database Record (c) 2010 APA, all rights reserved)