Metacognitive components of visual search in children

Two studies examined children's increasing ability to analyze tasks in terms of the perceptual features that affect task difficulty. Of particular interest was any understanding that perceptual confusions occur during the search for an object surrounded by objects similar in shape or color to that object. In Study 1, 32 pre-schoolers constructed arrays intended to make the search easy or difficult. They made the search difficult simply by putting many toys into the toy box. In a forced-choice situation, they indicated that task difficulty was influenced by the number of objects and the similarity in color and shape of the targets and the surrounding objects. Study 2 more thoroughly examined knowledge of color and shape confusions, using 96 children from Grades K, 1, 3, and 4, assigned to two age groups. The older children but not the younger ones showed a significant understanding of color and shape confusions. Both age groups understood that performance is affected by a person's interest level and degree of attention to the task. The results were discussed in terms of the accessibility of the children's knowledge under different conditions.     

Interactions of signal and background variables in visual processing

Three variables which determine the opportunities for signal-noise confusions, display size (D), number of redundant signals per display (N), and number of alternative signals (A) were studied in relation to nature of the noise elements, confusable or nonconfusable with signals. Data were obtained in a forced-choice visual detection situation, the displays being linear arrays of letters on a CRT screen. For all three performance measures used, frequency of correct detections and correct and error latencies, strong interactions were obtained between all of the other variables and signal-noise confusability. The functions obtained, together with other data bearing on the role of confusions and on spatial relations among characters within the display, suggest a model whose initial phase is a parallel feature extraction process involving inhibitory relations among input channels.     

A dual-task analysis of detection accuracy for the case of high target-distractor similarity: Further evidence for independent processing

Previous studies of visual detection performance indicate that perceptual span has a negligible effect on detection accuracy; hence, previous results suggest that individual characters within a multielement array are perceived independently. In this study, additional experimental factors were examined in order to determine whether conditions exist in which perceptual span influences detection performance: targets and distractors were chosen to be maximally similar, and detection accuracy was studied in relation to display size, target redundancy, and homogeneity of distractor characters. To test for perceptual span effects, a three-state model was proposed which incorporates the assumption that individual characters are perceived independently. The model may be applied to (a) both yes-no and forced-choice tasks, and (b) the case when effects of display characteristics differ for response alternatives. Predictions based on the three-state model agree satisfactorily with observed proportions. Moreover, interactions between display characteristics and response alternatives accord well with model predictions, and accuracy differences between subjects are consistent with individual differences in model parameters. The results provide further evidence for the independence assumption and illustrate additional conditions for which perceptual span has a negligible effect on detection accuracy.     

高中二年级学生中文阅读知觉广度的眼动研究

采用“呈现随眼动变化技术”对高中二年级学生中文阅读的知觉广度进行了眼动研究。结果发现,高中二年级学生的阅读知觉广度具有不对称性,大约为注视点左侧一个或两个汉字到注视点右侧三个或四个汉字的空间;高中二年级学生在正常阅读中的眼跳距离约为三个汉字的空间,在连续注视的过程中知觉广度有较小范围的重叠。     

不同水平五年级维吾尔族学生母语阅读知觉广度

本研究以眼动仪为工具,借助移动窗口技术,比较了16名高阅读水平和14名低阅读水平的五年级维吾尔族小学生维吾尔语阅读知觉广度的大小及其对称性。结果发现:高阅读水平学生的知觉广度为注视点左侧8~11个字符到右侧2~3个字符,而低阅读水平学生的知觉广度为注视点左侧8~11个字符到右侧2个字符。在本研究条件下,可得出以下结论:(1)五年级不同阅读水平的学生维吾尔语阅读知觉广度都具有不对称性,左侧范围大于右侧;(2)阅读水平高的学生其阅读知觉广度略大于低阅读水平的学生,差异主要体现在右侧知觉广度。     

Unconscious color priming occurs at stimulus- not percept-dependent levels of processing

Although past studies have shown that visual information can be processed without awareness, the types and levels of this processing have yet to be determined. We used metacontrast masking to explore unconscious priming effects of white, blue, and green stimuli generated on a color video display. We found that a white prime tends to act more like a green than a blue one. Color confusions among unmasked and masked primes and calibrations of the display phosphors show that physical rather than perceptual properties of the stimuli best explain the white prime's effects. We conclude that unconscious color priming in normal observers occurs at early wavelength-dependent levels of processing prior to later color-percept-dependent levels.     

Dynamic shifts of pigeon local/global attention

It has previously been shown that pigeons can shift attention between parts and wholes of complex stimuli composed of larger, "global" characters constructed from smaller, "local" characters. The base-rate procedure used biased target level within any condition at either the local or global level; targets were more likely at one level than at the other. Biasing of target level in this manner demonstrated shifts of local/global attention over a time span consisting of several days with a fixed base rate. Experiment 1 examined the possibility that pigeons can shift attention between local and global levels of perceptual analysis in seconds rather than days. The experiment used priming cues the color of which predicted on a trial-by-trial basis targets at different perceptual levels. The results confirmed that pigeons, like humans, can display highly dynamic stimulus-driven shifts of local/global attention. Experiment 2 changed spatial relations between features of priming cues and features of targets within a task otherwise similar to that used in experiment 1. It was predicted that this change in cues might affect asymmetry but not the occurrence of a priming effect. A priming effect was again obtained, thereby providing generality to the claim that pigeons can learn that trial-by-trial primes predict targets at different levels of perceptual analysis. Pigeons can display perceptual, stimulus-driven priming of a highly dynamic nature. Electronic Publication     

小学五年级学生汉语阅读知觉广度的眼动研究

采用"呈现随眼动变化技术"对小学五年级学生的阅读知觉广度进行了眼动研究.结果发现,(1)小学五年级学生的阅读知觉广度具有不对称性.(2)小学五年级学生的阅读知觉广度为注视点左侧一个汉字到注视点右侧两个或三个汉字的空间.     

小学五年级语文学优生与学困生阅读知觉广度的眼动研究

本研究以眼动仪为工具,采用移动窗口范式来考察小学五年级语文学优生和学困生的阅读知觉广度。实验结果发现,小学五年级语文学优生的阅读知觉广度范围为注视字左侧一个汉字到注视字右侧三个汉字,小学五年级语文学困生的阅读知觉广度范围为注视字左侧一个汉字到注视字右侧两个汉字。小学五年级语文学优生的阅读知觉广度比学困生更大。     

Target position and practice in the identification of letters in varying contexts: A word superiority effect

A forced-choice detection paradigm controlling for postperceptual inference was used to investigate letter identification in three-position displays. Letters from a predesignated set of four targets appeared singly, in strings of noise characters, in unpronounceable nonsense strings, and in words. Subjects knew which context would occur, but did not know which of the three display positions would contain the target. Correct detection data were collected at constant exposure duration over five testing sessions. Overall identification accuracy was higher in words than in all other contexts, the first word superiority effect to be found with targets specified in advance since Reicher’s (1969). This effect remained constant over sessions. An interaction between context type and target position showed enhanced accuracy for initial and terminal letters in words, but depressed accuracy at initial and terminal positions in other contexts. This was interpreted to mean that prior knowledge of context is used to alter the dynamics of perceptual analysis.     

大小字号的文本对中文读者眼动模式和阅读知觉广度的影响

摘 要 研究以眼动仪为工具,采用移动窗口范式考察不同字号文本对读者阅读知觉广度和眼动模式的影响。实验结果发现,被试阅读大、小字号文本时的阅读知觉广度都是四个字。字号大小不影响读者的阅读知觉广度,但是影响读者的眼动模式。具体表现为：被试阅读小号字文本的平均注视时间、总注视时间比大号字文本长,平均眼跳距离更短,相对眼跳距离（单位为字的个数）更长,注视次数更多。     

On selection in vision

Summary The discrepancy between the capabilities of perceptual systems and effector systems makes mechanisms necessary that can selectively designate a subset of the perceptual information available to control an action. In vision, since foveation is neither sufficient nor necessary for this selection, central selection mechanisms have to be postulated. This study is concerned with the question of at what level this central selection takes place in one type of task, the partial-report bar-probe task. Two theories are relevant: early selection theories, asserting that central selection operates in a stage containing rapidly decaying precategorical visual information, and late selection theories, arguing that central selection operates in a stage containing abstract categorical information. A prediction following from the assumptions of early selection theories, but not of late selection theories, is that in bar-probe tasks the function relating the number of visual confusions to probe delays has to exhibit an inverted-U shape. This prediction was tested in five experiments, two with colors as items and three with letters. In all experiments, the proportion of visual confusions first increased with increasing probe delays and then decreased with still larger probe delays. The results support the early selection theories for small probe delays. For larger probe delays, late selection has to be postulated.     

Instrumentation designed to simulate the effects of prisms used in studies of visual rearrangement

A system is described which simulates some of the visual rearrangements and changes in sensorimotor relations that occur when experimental subjects move their eyes while looking through a contact lens with a prism attached. The simulated system is more convenient than a system based on the use of a contact lens, and it is based on measures of eye movement that are important in research on the perceptual effects of visual rearrangement. The effects that occur are reviewed in this paper. We also show in detail how the artificial system, which has an eye movement monitor interfaced with a computer and display, simulates the former effects. The data show that experimental subjects who experience visual rearrangement by simulated means manifest the same kind of perceptual adaptation produced in studies in which visual rearrangement is generated by means of a prism mounted on a contact lens.     

Do letter features migrate? A note of caution

Summary The feature-integration model of visual information processing (Treisman & Gelade, 1980) predicts perceptual errors based on the incorrect grouping of stimulus features in multi-element displays. Experiment 1 examined the frequency of such errors with a tachistoscopic bar probe task using letters and novel patterns with a production response. A substantial proportion of the errors did involve figures that were not present in the display but contained combinations of features which had been present. Such errors were especially prominent with novel patterns. The results with letters suggested that such responses were due to guessing, not feature migration, and this was confirmed by Experiment 2. In the second study, responses were collected for single character displays but were scored as if they had been responses to the multielement displays in Experiment 1. The results showed the same high proportion of illusory conjunction errors as the previous results and it was concluded that both results were due to guessing. Spatial confusions in the bar probe task with letters appear to involve whole characters, not character features.This research was supported by grant A-9581 from the National Science and Engineering Council of Canada to the senior author. This research was reported as a paper to the annual meeting of the Canadian Psychological Association, Toronto, 1981. Ian Morrison is now a post-doctoral fellow at the Department of Psychology, Carnegie-Mellon University.     

Age of acquisition affects early orthographic processing during Chinese character recognition

Three experiments investigated age of acquisition (AoA) effects on early orthographic processing during Chinese character recognition. In Experiment 1, we measured the accuracy of identification of brief masked characters, accuracy was higher for early compared to late acquired characters. In Experiment 2, the visual duration threshold (VDT) was measured for both early and late acquired Chinese characters. The results showed that early acquired characters were successfully identified at shorter display durations than late acquired characters. Significant AoA effects were also found in Experiment 3, using a lexical decision task requiring mainly orthographic processing (discriminating real Chinese characters from orthographically illegal and unpronounceable characters). In summary, three experiments provide converging empirical evidence, for AoA effects on the early orthographic processing stages of Chinese character recognition. These results suggest that AoA effects during word identification go beyond the phonological or semantic processing stages. These results aslo provide cross-linguistic evidence for an AoA effect on early perceptual processing during identification.     

Perceiving emotion from a talker: How face and voice work together

The experiment investigated how the addition of emotion information from the voice affects the identification of facial emotion. We presented whole face, upper face, and lower face displays and examined correct recognition rates and patterns of response confusions for auditory-visual (AV), auditory-only (AO), and visual-only (VO) expressive speech. Emotion recognition accuracy was superior for AV compared to unimodal presentation. The pattern of response confusions differed across the unimodal conditions and across display type. For AV presentation, a response confusion only occurred when such a confusion was present in each modality separately, thus response confusions were reduced compared to unimodal presentations. Emotion space (calculated from the confusion data) differed across display types for the VO presentations but was more similar for the AV ones indicating that the addition of the auditory information acted to harmonize the various VO response patterns. These results are discussed with respect to how bimodal emotion recognition combines auditory and visual information.     

What various kinds of errors tell us about lateral masking effects

Error analyses were conducted to study processes underlying lateral masking effects. Location errors (i.e., confusions with a flanking letter) occurred at a rate higher than chance, and they increased with increasing eccentricity and with decreasing spacing. In longer strings, confusions with a flanker directly adjacent to the target (which is itself laterally masked) were more frequent than with a far flanker, and these confusions also increased with increasing eccentricity and with decreasing spacing indicating that identification of the letter's form is not necessarily disturbed by adjacent characters. This was confirmed in a whole report task, where there was better recognition performance for the central letter than in partial report. Whereas in partial report, the left flanker was more often confused with the target than the right one, in whole report, the left-most letter was recognized best. The data provide evidence that positional uncertainty contributes to lateral masking effects, and that a substantial portion of positional uncertainty occurs after having identified the letter's forms.     

Age-related changes in selective attention and perceptual load during visual search

Three visual search experiments were conducted to test the hypothesis that age differences in selective attention vary as a function of perceptual load (E. A. Maylor & N. Lavie, 1998). Under resource-limited conditions (Experiments 1 and 2), the distraction from irrelevant display items generally decreased as display size (perceptual load) increased. This perceptual load effect was similar for younger and older adults, contrary to the findings of Maylor and Lavie. Distraction at low perceptual loads appeared to reflect both general and specific inhibitory mechanisms. Under more data-limited conditions (Experiment 3), an age-related decline in selective attention was evident, but the age difference was not attributable to capacity limitations as predicted by the perceptual load theory.     

绕口令效应对汉语阅读影响的眼动研究

绕口令效应指无论朗读还是默读,绕口令的阅读时间都长于正常句子的阅读时间。本研究采用Eyelink 2000型眼动仪,通过两个实验考察汉语阅读中的绕口令效应及其对知觉广度的影响。实验1结果表明:与阅读非绕口令相比,绕口令的阅读时间和注视次数均显著增加而阅读速度和平均眼跳幅度均显著下降。实验2结果表明:绕口令的知觉广度为注视点右侧1~2个汉字,控制句的知觉广度为注视点右侧2~3个汉字。结果说明汉语中存在绕口令效应,使读者知觉广度变小,阅读效率下降。。