The role of surface discontinuity and shape in 4-month-old infants' object segregation

This research examined whether 4-month-old infants use a discontinuity in an object's front surface to visually segregate a display into two separate objects, and whether object shape enables its use. In Experiment 1, infants saw a three-dimensional display composed of two parts with distinctly different shapes. Two groups of infants saw a display in which these two shapes were divided by a visible discontinuity in the front surface (i.e., a boundary between the two objects). One of these groups saw the display move apart at the discontinuity when a gloved hand pulled one object; the second group saw the two objects move together as a single unit. A third group saw a modified version of this display that had no discontinuity present. The results suggested that infants regarded the discontinuity as an indication that the display could be composed of more than one object. In Experiment 2, infants saw the same display, but with a shape that did not highlight the discontinuity. The infants in this study showed no evidence of using the discontinuity. Together, the findings suggest that 4-month-old infants use the surface discontinuity between two objects as an indication that multiple objects could be present in a display, but only when scanning the outer edges of the display leads them to attend to it.     

Eye movements and display change detection during reading

In the boundary change paradigm (Rayner, 1975), when a reader's eyes cross an invisible boundary location, a preview word is replaced by a target word. Readers are generally unaware of such changes due to saccadic suppression. However, some readers detect changes on a few trials and a small percentage of them detect many changes. Two experiments are reported in which we combined eye movement data with signal detection analyses to investigate display change detection. On each trial, readers had to indicate if they saw a display change in addition to reading for meaning. On half the trials the display change occurred during the saccade (immediate condition); on the other half, it was slowed by 15-25 ms (delay condition) to increase the likelihood that a change would be detected. Sentences were presented in an alternating case fashion allowing us to investigate the influence of both letter identity and case. In the immediate condition, change detection was higher when letters changed than when case changed corroborating findings that word processing utilizes abstract (case independent) letter identities. However, in the delay condition (where d' was much higher than the immediate condition), detection was equal for letter and case changes. The results of both experiments indicate that sensitivity to display changes was related to how close the eyes were to the invalid preview on the fixation prior to the display change, as well as the timing of the completion of this change relative to the start of the post-change fixation.     

Attentional capture of objects referred to by spoken language

Participants saw a small number of objects in a visual display and performed a visual detection or visual-discrimination task in the context of task-irrelevant spoken distractors. In each experiment, a visual cue was presented 400 ms after the onset of a spoken word. In experiments 1 and 2, the cue was an isoluminant color change and participants generated an eye movement to the target object. In experiment 1, responses were slower when the spoken word referred to the distractor object than when it referred to the target object. In experiment 2, responses were slower when the spoken word referred to a distractor object than when it referred to an object not in the display. In experiment 3, the cue was a small shift in location of the target object and participants indicated the direction of the shift. Responses were slowest when the word referred to the distractor object, faster when the word did not have a referent, and fastest when the word referred to the target object. Taken together, the results demonstrate that referents of spoken words capture attention.     

Visual short-term memory operates more efficiently on boundary features than on surface features

A change detection task was used to estimate the visual short-term memory storage capacity for either the orientation or the size of objects. On each trial, several,objects were briefly presented, followed by a blank interval and then by a second display of objects that either was identical to the first display or had a single object that was different (the object changed either orientation or size, in separate experiments). The task was to indicate whether the two displays were the same or different, and the number of objects remembered was estimated from the percent correct on this task. Storage capacity for a feature was nearly twice as large when that feature was defined by the object boundary, rather than by the surface texture of the object. This dramatic difference in storage capacity suggests that a particular feature (e.g., right tilted or small) is not stored in memory with an invariant abstract code. Instead, there appear to be different codes for the boundary and surface features of objects, and memory operates on boundary features more efficiently than it operates on surface features.     

Reversal of object-based benefits in visual attention

In divided-attention tasks, observers must make speeded (or near threshold accuracy) judgements concerning two target features in a display. Typically, when the two features belong to the same object they are more rapidly judged than when they belong to separate objects, a pattern of findings referred to here as a “same-object benefit”. However, we note here that many of these studies share common features, in particular the use of pre-exposed, outline, and/or overlapping objects, and their findings may not generalize to other types of display. Building substantially on previous work by Davis, Welch, Holmes, and Shepherd (2001), we show in four new studies that once these features are not present in a divided-attention task, no same-object benefits are reported. Rather we now find “same-object costs”, where features belonging to a single object are less rapidly judged than features belonging to separate objects.     

Inhibitory processes in young and older adults in a picture-word task

Abstract

The present study examines changes in healthy young and healthy older adults in the ability to inhibit partially activated information in a picture/word interference paradigm. On each trial, subjects received a cue (i.e., the word PICTURE or WORD) indicating which of two stimuli the subject should attend to in an upcoming picture/word display. the display always contained a superimposed picture and word (e.g., a picture of a DEER with the word TEA printed on it). Following display offset, and depending upon the initial precue, either a test picture (e.g., KETTLE) or a test word (e.g., MOOSE) was presented. the subject's task was to determine as quickly and as accurately as possible whether the test stimulus was related to the cued dimension of the earlier picture/word display. the speed to reject an unrelated test item (e.g., picture of a KETTLE when the precue was PICTURE) that was related to the ignored dimension of the picture/word display (e.g., the word TEA in the picture/word display) was used as an index of the efficiency of the inhibitory system. the results indicated that older adults had more difficulty than younger adults inhibiting a to-be-ignored word when it was related to a picture test item, but did not have more difficulty inhibiting a to-be-ignored picture when it was related to a word test item. the results indicate that an age-related deficit in the control of interfering information is dependent upon the fluency of the processing routes.     

Playing on the typewriter, typing on the piano: manipulation knowledge of objects

Two experiments investigated sensory/motor-based functional knowledge of man-made objects: manipulation features associated with the actual usage of objects. In Experiment 1, a series of prime-target pairs was presented auditorily, and participants were asked to make a lexical decision on the target word. Participants made a significantly faster decision about the target word (e.g. ‘typewriter’) following a related prime that shared manipulation features with the target (e.g. ‘piano’) than an unrelated prime (e.g. ‘blanket’). In Experiment 2, participants' eye movements were monitored when they viewed a visual display on a computer screen while listening to a concurrent auditory input. Participants were instructed to simply identify the auditory input and touch the corresponding object on the computer display. Participants fixated an object picture (e.g. “typewriter”) related to a target word (e.g. ‘piano’) significantly more often than an unrelated object picture (e.g. “bucket”) as well as a visually matched control (e.g. “couch”). Results of the two experiments suggest that manipulation knowledge of words is retrieved without conscious effort and that manipulation knowledge constitutes a part of the lexical-semantic representation of objects.     

Object perception and object-directed reaching in infancy

Five-month-old infants were presented with a small object, a larger object, and a background surface arranged in depth so that all were within reaching distance. Patterns of reaching for this display were observed, while spatial and kinetic properties of the display were varied. When the infants reached for the display, they did not reach primarily for the surfaces that were nearer, smaller, or presented in motion. The infants reached, instead, for groups of surfaces that formed a unit that was spatially connected and/or that moved as a whole relative to its surroundings. Infants reached for the nearer of two objects as a distinct unit when the objects were separated in depth or when one object moved relative to the other. They reached for the two objects as a single unit when the objects were adjacent or when they moved together. The reaching patterns provided evidence that the infants organized each display into the kind of units that adults call objects: manipulable units with internal coherence and external boundaries. Infants, like adults, perceived objects by detecting both the spatial arrangements and the relative movements of surfaces in the three-dimensional layout.     

Linguistic focus and memory: An eye movement study

We report an eyetracking study investigating the effects of linguistic focus on eye movements and memory during two readings of a text. Across two presentations of the text, a critical word either changed to a semantically related word or remained unchanged. Focus on the critical word was manipulated using context. Eye movements were monitored during reading, and there was a secondary task of detecting the word change. Results indicated that when a word changed, participants were more successful at detecting it when it was in focus. In the second display, there were more fixations and longer viewing times on a changed than on an unchanged word, but only when the critical word was in focus; eye movement data for changed and unchanged words did not differ when the word was not in focus. We suggest that linguistic focus leads to more detailed lexical semantic representations but not more effortful initial encoding of information.     

On the spatial extent of attention in object-based visual selection

A new test was devised to avoid previous confounds in measures of object-based limits on divided visual attention. The distinction between objects was manipulated across a wide spatial extent. Target elements appeared on the same object only when far apart, and appeared close only when on different objects, so that object effects could not be reduced to spatial effects, nor vice versa. Subjects judged whether two odd elements within a display of two dashed lines were the same or different. They performed better when the target elements were far apart on a common line rather than on two distinct lines, even though the latter arrangement was more likely. Thus, nonstrategic object-based limits on divided attention can arise even across large distances. However, when subjects were precued to expect targets in a narrow region of the display, the object effect was eliminated, implying that object-based selection may only operate within spatially attended regions.     

Perceiving binocular depth with reference to a common surface

A common surface is a spatial regularity of our terrestrial environment. For instance, we walk on the common ground surface, lay a variety of objects on the table top, and display our favorite paintings on the wall. It has been proposed that the visual system utilizes this regularity as a reference frame for coding objects' distances. Presumably, by treating the common surface as such--i.e. an anticipated constant--the visual system can reduce its coding redundancy, and divert its resources to representing other information. For intermediate-distance space perception, it has been found that absolute distance judgment is most accurate when a common ground surface is available. Here we explored if the common surface also serves as the reference frame for the processing of binocular-disparity information, which is a predominant cue for near-distance space perception. We capitalized on an established observation where the perceived slant of a surface with linear binocular-disparity gradient is underestimated. Clearly, if the visual system utilizes this incorrectly represented slant surface as a reference frame for coding the objects' locations, the perceived depth separation between the objects will be adversely affected. Our results confirm this, by showing that the depth judgment of objects (two laterally separated vertical lines) on, or in the vicinity of, the surface is underestimated. Furthermore, we show that the impact of the common surface on perceived depth separation most likely occurs at the surface-representation level where the visual surface has been explicitly delineated, rather than at the earlier disparity-processing level.     

The role of cognitive factors in the rod-and-frame effect

We compared the contribution and the effectiveness of modulating the orientation perception of two types of visual information: the visual frame and the visual polarity of objects. In experiment 1, we examined the effect of a square frame, a mouse, an elephant, and a map of France on the apparent vertical. In the upright position, despite the presence of tilted individual component features, the visual objects had no illusory visual tilt effects. When tilted, these objects had a substantial effect on the direction that appeared to be vertical. However, rod-setting errors were smaller in the inducing objects than when observed with the frame display. In the second experiment, the results of experiment 1 were replicated with a meaningful circular contour--a porthole and a clock. The presence of the external circular contour did not abolish the illusion on the apparent vertical. Moreover, in experiment 3, a clock whose numbers were displaced and not tilted--to avoid the possible tilt influence of visual cues--was also able to deflect the subjective visual vertical. This finding suggests that through top-down processing shapes can act as a framework which serves as a reference influencing the perceived orientation of the inner objects.     

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.     

Does a color difference between parts impair the perception of a whole? A similarity between simultanagnosia patients and healthy observers

In three experiments, participants decided whether a Star of David shape was present among distractors. Although the participants were instructed to ignore the colors in the display, detection was slower when each triangle of the Star of David was printed in a different color than when the Star of David was printed in a uniform color or when each triangle was in two colors. Extending the object file theory, we suggest that when the parts of an object are distinguished by a color difference and are perceived as separate objects, the perception of the whole object, which is composed of these same parts, is damaged. One interpretation within object file theory is that when the visual system represents the location of a complex object as occupied by identity tags for its different parts, it cannot also link the same location to the identity of the complex object. A new object file must then be created.     

Framing effects on metacognitive monitoring and control

Three experiments explored the contribution of framing effects on metamemory judgments. In Experiment 1, participants studied word pairs. After each presentation, they made an immediate judgment of learning (JOL), framed in terms of either remembering or forgetting. In the remember frame, participants made judgments about how likely it was that they would remember each pair on the upcoming test. In the forget frame, participants made judgments about how likely it was that they would forget each pair. Confidence differed as a result of the frame. Forget frame JOLs, equated to the remember frame JOL scale by a 1-judgment conversion, were lower and demonstrated a smaller overconfidence bias than did remember frame JOLs. When judgments were made at a delay, framing effects did not occur. In Experiment 2, people chose to restudy more items when choices were made within a forget frame. In Experiment 3, people studied Spanish—English vocabulary pairs ranging in difficulty. The framing effect was replicated with judgments and choices. Moreover, forget frame participants included more easy and medium items to restudy. These results demonstrated the important consequences of framing effects on assessment and control of study.     

Evidence for two components of object-based selection

A wealth of research has shown that observers can bias visual processing toward specific locations, but the role of object-based selection is less clear. In support of object-based selection, previous research has shown that when two objects are presented simultaneously, observers are better at reporting two attributes from one of the objects than one attribute from each object. However, there has been controversy over whether this effect is best explained by object-based selection or spatial selection. Our work suggests that there are two separate components of selection in this task: (a) a spatial component that is observed when the relevant targets are cued for observers before the onset of the stimulus display and (b) an object-based component that can still be observed when the first component has been eliminated. The latter effect replicates the initial evidence in favor of object-based selection, and can be demonstrated even when the relevant targets are cued after the offset of the target stimuli.     

What is enumerated by subitization mechanisms?

Subitization, the rapid enumeration of small numbers of objects, is often held to reflect a general ability to process three or four items simultaneously. However, questions as to which types of visual representations count as items for subitization have, thus far, received relatively little attention. In several new experiments, we instructed participants to enumerate three or four colored regions in a display. In some trials, all of these regions belonged to separate visual objects, whereas in others, two or more belonged to the same object(s). We found far slower enumeration in the latter case than in the former case, a result that cannot be attributed to Stroop interference from the number of attended objects in a display. We conclude that subitization mechanisms cannot operate on small fragments of shape and color alone, even when such fragments are easily individuated from one another. Rather, such mechanisms are compelled to operate on object representations.     

联结再认中双语者第二语言记忆优势效应

研究使用ERPs技术, 考察了双语者在联结再认中是否存在第二语言记忆优势效应。实验要求被试完成维吾尔语(L1)和汉语(L2)两类“学习-测试”任务。学习阶段要求被试学习混合呈现的复合词和无关词, 测验阶段要求被试区分“旧”、“重组”或“新”词对。行为结果发现：(1)复合词中, L2的正确率高于L1, L2的反应时快于L1; 无关词中, L2的正确率与L1无显著差异, 但L2的反应时快于L1。(2) 在L2和L1中, 复合词的正确率均高于无关词, 反应时均快于无关词。ERPs结果发现：(1)在高整合条件下, L2仅诱发了FN400效应, L1诱发了FN400效应和LPC效应; 在低整合条件下, L2和L1都只诱发了LPC效应。(2)在时间进程上, L2和L1分别在650 ms和900 ms完成联结关系的提取。上述结果表明, 在高整合条件下, 双语者在联结再认中存在L2记忆优势。此外, 实验结果也从双语角度证明了, 整合编码能促进熟悉性在维吾尔语联结再认中发挥作用。本研究结果的实践意义在于, 为我国少数民族学生习得国家通用语言文字提供了认知神经科学依据。     

Lexical- and perceptual-based object effects in the two-rectangle cueing paradigm

Previous studies demonstrate that attentional selection can be object-based, in which the object is defined in terms of Gestalt principles or lexical organizations. Here we investigate how attentional selection functions when the two types of objects are manipulated jointly. Experiment 1 replicated Li and Logan (2008) by showing that attentional shift between two Chinese characters is more efficient when they form a compound word than when they form a nonword. Experiment 2A presented characters either alone or within rectangles (Egly, Driver, & Rafal, 1994) and the characters in a rectangle formed either a word or a nonword. Experiment 2B differed from Experiment 2A in that the two characters forming a word were in different rectangles. Experiment 3A presented the two characters of a word either within a rectangle or in different rectangles. Experiment 3B used the same design as Experiment 3A but presented stimuli of different types in random orders, rather than in blocks as in Experiments 2A, 2B and 3A. In blocked presentation, detection responses to the target color on a character were faster when this character and the cue character formed a word than when they did not, and the size of this lexical-based object effect did not vary according to whether the two characters were presented alone or within or between rectangles. In random presentation, however, the lexical-based object effect was diminished when the two characters of a word were presented in different rectangles. Overall, these findings suggest that the processes that constrain attention deployment over conjoined objects can be strategically adjusted.