Speech perception and memory coding in relation to reading ability

Previous work has demonstrated that children who are poor readers have short-term memory deficits in tasks in which the stimuli lend themselves to phonetic coding. The aim of the present study was to explore whether the poor readers' memory dificit may have its origin in perception with the encoding of the stimuli. Three experiments were conducted with third grade good and poor readers. As in earlier experiments, the poor readers were found to perform less well on recall of random word strings and to be less affected by the phonetic characteristics (rhyming or not rhyming) of the items (Experiment 1). In addition, the poor readers produced more errors of transposition (in the nonrhyming strings) than did the good readers, a further indication of the poor readers' problems with memory for order. The subjects were tested on two auditory perception tasks, one employing words (Experiment 2) and the other nonspeech environmental sounds (Experiment 3). Each was presented under two conditions: with a favorable signal-to-noise ratio and with masking. The poor readers made significantly more errors than the good readers when listening to speech in noise, but did not differ in perception of speech without noise or in perception of nonspeech environmental sounds, whether noise-masked or not. Together, the results of the perception studies suggest that poor readers have a perceptual difficulty that is specific to speech. It is suggested that the short-term memory deficits characteristic of poor readers may stem from material-specific problems of perceptual processing.     

知觉组织对时序知觉的双重影响:同时判断任务的证据

本研究探讨知觉组织对时序知觉的双重影响。实验采用三条线段构成的C形为实验材料,操纵图形朝向和SOA水平(实验1和实验2)、图形颜色(实验3)以及反应限制(实验4),要求被试完成同时判断任务。结果发现,在不同的SOA条件下,图形对向条件的同时判断频率均显著高于图形反向条件(实验1),即使在知觉组织线索弱化时这种现象仍然存在(实验2和实验3),而且知觉组织对时序知觉的影响不是由于被试的反应偏向导致的(实验4)。结果说明知觉组织对时序知觉存在双重影响:当两个刺激同时出现时,知觉组织能够提高时序知觉表现; 而当两个刺激非同时出现时,知觉组织显著降低时序知觉表现。     

视觉加工速度、瞬间信息整合特征与汉语学习困难

采用因素实验设计,通过与正常学生与听力损伤学生对比实验研究,探讨汉语学习困难学生视觉加工速度和视觉瞬间信息整合的特征。结果表明:(1)汉语学习困难学生存在基本视觉加工速度不足以及汉语语言文字视觉加工的特异性困难;(2)汉语学习困难学生需要更长时间整合瞬间视觉信息,从而影响了其加工的速度;(3)适当延长视觉刺激整合的时间,可以有效提高其视觉加工的效率。这些结果对改善学生的汉语学习困难具有一定的指导意义。     

Visual information processing in relation to age and to reading ability.

Temporal aspects of early visual information processing were studied developmentally in good and in poor reading male subjects ranging in age from 7 to 13 years. Forced-choice temporal integration and backward masking tasks, respectively, were utilized to assess duration of visual persistence and of relative rate of visual information processing. The results did not reveal differences in either visual persistence or processing rate in relation to reading ability at any age level studied. However, processing rate was found to increase markedly with chronological age in both the good and the poor readers while visual persistence did not vary significantly. The findings were discussed in relation to earlier work and in relation to current theoretical formulations of visual information processing.     

知觉组织影响时序知觉的认知机制:ERP研究的证据

以往研究显示,知觉组织影响时序知觉,采用ERP技术拟探讨知觉组织影响时序知觉的认知机制。采集23名被试完成同时判断任务的脑电数据。行为结果发现,知觉组织影响时序知觉,具体表现为知觉组织条件的同时判断频率显著高于非知觉组织条件。ERPs结果发现,在P1和P2成分上,知觉组织条件与非知觉组织条件引发的波幅没有显著差异; 而在N1成分上,知觉组织条件诱发的N1波幅显著大于非知觉组织条件。这表明,知觉组织对时序知觉的影响可能发生在视觉刺激加工的早期阶段,视觉刺激的知觉组织先于时序信息加工。     

Crossmodal duration perception involves perceptual grouping, temporal ventriloquism, and variable internal clock rates

Here, we investigate how audiovisual context affects perceived event duration with experiments in which observers reported which of two stimuli they perceived as longer. Target events were visual and/or auditory and could be accompanied by nontargets in the other modality. Our results demonstrate that the temporal information conveyed by irrelevant sounds is automatically used when the brain estimates visual durations but that irrelevant visual information does not affect perceived auditory duration (Experiment 1). We further show that auditory influences on subjective visual durations occur only when the temporal characteristics of the stimuli promote perceptual grouping (Experiments 1 and 2). Placed in the context of scalar expectancy theory of time perception, our third and fourth experiments have the implication that audiovisual context can lead both to changes in the rate of an internal clock and to temporal ventriloquism-like effects on perceived on- and offsets. Finally, intramodal grouping of auditory stimuli diminished any crossmodal effects, suggesting a strong preference for intramodal over crossmodal perceptual grouping (Experiment 5).     

Seeing what they read and hearing what they say: Readers’ representation of the story characters’ world

Do readers “see” the words that story characters read and “hear” the words that they hear? Just as priming effects are reduced when stimuli are presented cross-modally on two different occasions, we found reduced transfer effects when story characters were described as experiencing stimuli cross-modally. In Experiment 1, a repeated phrase was described as being part of a spoken message in both Story A and Story B, and transfer effects were found. In Experiment 2, in contrast, when the phrase was described as a written note in one story and a spoken message in the other, reading-time results indicated that readers did not retrieve the meaning of the repeated phrase. The results are consistent with findings indicating that visual imagery simulates visual processing and that auditory imagery simulates auditory processing. We conclude that readers mentally simulate the perceptual details involved in story characters’ linguistic exchanges.     

The relationship between auditory temporal processing,phonemic awareness,and reading disability

Recent research suggests an auditory temporal deficit as a possible contributing factor to poor phonemic awareness skills. This study investigated the relationship between auditory temporal processing of nonspeech sounds and phonological awareness ability in children with a reading disability, aged 8-12 years, using Tallal's tone-order judgement task. Normal performance on the tone-order task was established for 36 normal readers. Forty-two children with developmental reading disability were then subdivided by their performance on the tone-order task. Average and poor tone-order subgroups were then compared on their ability to process speech sounds and visual symbols, and on phonological awareness and reading. The presence of a tone-order deficit did not relate to performance on the order processing of speech sounds, to poorer phonological awareness or to more severe reading difficulties. In particular, there was no evidence of a group by interstimulus interval interaction, as previously described in the literature, and thus little support for a general auditory temporal processing difficulty as an underlying problem in poor readers. In this study, deficient order judgement on a nonverbal auditory temporal order task (tone task) did not underlie phonological awareness or reading difficulties.     

Visual pattern perception: a multidimensional analysis of development of children's reading skills

This study was designed to assess the extent to which there are visual pattern processing deficits which are related to differential reading skill of young children. Discrimination problems were constructed using visual patterns with features known to be processed differentially by the central nervous system based upon neurophysiological data. Analysis of variance and multidimensional scaling techniques were used to analyze the discrimination latencies of kindergarten through third grade children (12 per grade) who were classified either as good or poor readers. The results show that there are no pattern-specific effects which discriminate good from poor readers. Rather, good readers process all patterns more efficiently than do poor readers, and efficiency improves with age for all readers studied. This suggests that the locus of the reading deficit occurs at levels in the nervous system beyond where pattern-feature processing occurs.     

Temporal grouping in auditory spatial serial memory

Grouping effects in serial recall have been widely studied with verbal stimuli, but hardly ever with spatial stimuli and not at all with auditory spatial stimuli. In Experiment 1, we examined the influence of combined temporal and pitch grouping on recall of the locations from which bursts of white noise were presented. Similar to findings in verbal studies, effects of the grouping manipulation were found in performance accuracy, in the nature of order errors, and in the timing of responses. Experiment 2 was designed to distinguish the role played by pitch grouping from that played by temporal grouping, through independent manipulation of the presence of a shift in pitch and that of a temporal gap. The results showed that the temporal grouping manipulation determined performance and the pitch grouping manipulation did not. Similarities between our findings and those of verbal studies, and implications for the understanding of serial memory are discussed.     

Visual perseveration in normal and mentally retarded children

Visual perseveration was investigated within mentally retarded and second, fifth, and eighth grade normal children (Ns = 12 each group). Subjects matched an auditorially presented click to the onset and offset of visually presented stimuli. Time differences between visual stimulus offset and the point at which subjects reported simultaneity of the click and visual stimulus offset was assumed to reflect visual perseveration. Results showed: (a) no differences between the normal children as a function of age; (b) no difference between groups for stimuli of 100 msec. or longer duration; and (c) retarded subjects judged stimuli of 20 and 50 msec. to be of shorter duration than did normal subjects. This highly specific distinction between retarded and normal subjects suggests a difference in an early stage of perceptual processing.     

Impaired sensitivity to dynamic stimuli in poor readers of a regular orthography

The mappings from grapheme to phoneme are much less consistent in English than they are for most other languages. Therefore, the differences found between English-speaking dyslexics and controls on sensory measures of temporal processing might be related more to the irregularities of English orthography than to a general deficit affecting reading ability in all languages. However, here we show that poor readers of Norwegian, a language with a relatively regular orthography, are less sensitive than controls to dynamic visual and auditory stimuli. Consistent with results from previous studies of English-readers, detection thresholds for visual motion and auditory frequency modulation (FM) were significantly higher in 19 poor readers of Norwegian compared to 22 control readers of the same age. Over two-thirds (68.4%) of the children identified as poor readers were less sensitive than controls to either or both of the visual coherent motion or auditory 2Hz FM stimuli.     

Word length,phonemic, and visual similarity effects in poor and normal readers

Serial order recall for visually and auditorily presented stimuli was examined in a group of 12-year-old poor readers and 7-year-old reading-age controls. With pictorial presentation, the poor readers showed a visual similarity effect, no word length effect, and a smaller phonemic similarity effect than that of controls. However, with visual presentation of printed words and with auditory presentation, poor readers showed word length and phonemic similarity effects of similar magnitude to that of controls. It is concluded that poor readers rely on visual information in tasks where the presented images are highly codable, and where verbal recoding is not obligatory, but that they will make use of phonological coding when the stimuli are not as easily codable visually in memory.     

Unconscious processing of color and form in metacontrast masking

Three experiments employed a metacontrast masking procedure to examine the extent and nature of priming effects from visual stimuli not consciously perceived. The results showed effects of unconscious stimuli on subsequent target responses that (1) were more consistent, reliable, and not subject to strategic control, as compared with consciously perceived stimuli (Experiment 1); (2) produced both facilitation and interference of subsequent processing (Experiment 2); and (3) did not influence indirect response-related levels of processing (Experiment 3). These results demonstrate that color and form attributes of unconscious stimuli are sufficiently registered within the visual system to influence behavior, and that some of these unconscious effects occur at early levels of stimulus encoding, prior to higher level perceptual and response-related processes.     

系列项目时间和空间信息学习的分组效应研究

运用顺序回忆方法考察分组对系列项目时间和空间信息学习的影响。包括两个实验,实验一考察简化时间上的分组,或事先告知被试分组规则的情况下,分组是否会有助于时间顺序信息的学习。结果发现,这两个操作对时间顺序信息学习的促进作用不显著。实验二考察了垂直维度上不同形式的分组对空间位置信息学习的影响。结果发现,不同的分组方式对空间位置信息学习所起的作用不同。本研究支持了时间和空间两类顺序信息学习的内在过程不同,不应该用同一理论机制进行解释。     

Visual training improves perceptual grouping based on basic stimulus features

Training on visual tasks improves performance on basic and higher order visual capacities. Such improvement has been linked to changes in connectivity among mediating neurons. We investigated whether training effects occur for perceptual grouping. It was hypothesized that repeated engagement of integration mechanisms would enhance grouping processes. Thirty-six participants underwent 15 sessions of training on a visual discrimination task that required perceptual grouping. Participants viewed 20?×?20 arrays of dots or Gabor patches and indicated whether the array appeared grouped as vertical or horizontal lines. Across trials stimuli became progressively disorganized, contingent upon successful discrimination. Four visual dimensions were examined, in which grouping was based on similarity in luminance, color, orientation, and motion. Psychophysical thresholds of grouping were assessed before and after training. Results indicate that performance in all four dimensions improved with training. Training on a control condition, which paralleled the discrimination task but without a grouping component, produced no improvement. In addition, training on only the luminance and orientation dimensions improved performance for those conditions as well as for grouping by color, on which training had not occurred. However, improvement from partial training did not generalize to motion. Results demonstrate that a training protocol emphasizing stimulus integration enhanced perceptual grouping. Results suggest that neural mechanisms mediating grouping by common luminance and/or orientation contribute to those mediating grouping by color but do not share resources for grouping by common motion. Results are consistent with theories of perceptual learning emphasizing plasticity in early visual processing regions.     

Visual search for global/local stimulus features in humans and baboons

Fagot and Deruelle (1997) demonstrated that, when tested with identical visual stimuli, baboons exhibit an advantage in processing local features, whereas humans show the “global precedence” effect initially reported by Navon (1977). In the present experiments, we investigated the cause of this species difference. Humans and baboons performed a visual search task in which the target differed from the distractors at either the global or the local level. Humans responded more quickly to global than to local targets, whereas baboons did the opposite (Experiment 1). Human response times (RTs) were independent of display size, for both local and global processing. Baboon RTs increased linearly with display size, more so for global than for local processing. The search slope for baboons disappeared for continuous targets (Experiment 2). That effect was not due to variations in stimulus luminance (Experiment 3). Finally, variations in stimulus density affected global search slopes in baboons but not in humans (Experiment 4). Overall, results suggest that perceptual grouping operations involved during the processing of hierarchical stimuli are attention demanding for baboons, but not for humans.     

Temporal order and processing acuity of visual,auditory, and tactile perception in developmentally dyslexic young adults

We studied the temporal acuity of 16 developmentally dyslexic young adults in three perceptual modalities. The control group consisted of 16 age- and IQ-matched normal readers. Two methods were used. In the temporal order judgment (TOJ) method, the stimuli were spatially separate fingertip indentations in the tactile system, tone bursts of different pitches in audition, and light flashes in vision. Participants indicated which one of two stimuli appeared first. To test temporal processing acuity (TPA), the same 8-msec nonspeech stimuli were presented as two parallel sequences of three stimulus pulses. Participants indicated, without order judgments, whether the pulses of the two sequences were simultaneous or nonsimultaneous. The dyslexic readers were somewhat inferior to the normal readers in all six temporal acuity tasks on average. Thus, our results agreed with the existence of a pansensory temporal processing deficit associated with dyslexia in a language with shallow orthography (Finnish) and in well-educated adults. The dyslexic and normal readers' temporal acuities overlapped so much, however, that acuity deficits alone would not allow dyslexia diagnoses. It was irrelevant whether or not the acuity task required order judgments. The groups did not differ in the nontemporal aspects of our experiments. Correlations between temporal acuity and reading-related tasks suggested that temporal acuity is associated with phonological awareness.     

Grouping reduces visual extinction: Neuropsychological evidence for weight-linkage in visual selection

Abstract

We tested two subjects following damage to right parietal cortex to see if their failure to detect a left visual stimulus in the presence of a simultaneous right stimulus (visual extinction) could be modulated by perceptual grouping between the left and right stimuli. Subjects performed a simple detection task for brief displays in which items could appear in the left or right visual field, both fields, or neither field. On trials in which items appeared in both fields, we found that left omissions (extinction errors) were dramatically reduced when the two items formed a good perceptual group, either on the basis of Gestalt factors such as similarity and symmetry (Experiment 1). or by forming a familiar configuration (Experiment 2). We suggest that extinction may be a spatially specific exaggeration of a normal attention limitation, in which the contralesional item is disadvantaged in the competition for selection. However, this obstacle to selection can be overcome if, as a result of grouping, ipsilesional and contralesional items become allies rather than competitors for selection.     

重复启动对时序知觉的影响

在时序判断任务中,重复启动导致被试把启动的靶刺激知觉为先出现的。知觉加工增强观和决策反应偏向观都试图解释其机制,但仍存在争议。本研究采用图形材料,通过三个实验系统考察了重复启动对时序知觉的影响。实验结果显示,启动和指导语都具有显著效应。这说明,重复启动对时序知觉的影响涉及知觉加工和决策水平两个方面。实验还首次发现,在启动的靶刺激先出现时发生了重复启动效应的反转。最后,研究提出了双加工表征匹配调节假说,用以综合解释目前的研究结果