Young children's processing of asymmetrical and symmetrical patterns

Dot patterns varying in type of symmetry (double symmetry, vertical symmetry, horizontal symmetry, and asymmetry) were presented tachistoscopically for 200 msec, followed by a patterned mask, to kindergarten, second-grade, and fourthgrade children. All subjects reported symmetrical patterns more accurately than asymmetrical patterns. Double symmetry patterns were reproduced more accurately than vertical symmetry patterns, and vertical symmetry patterns were reproduced more accurately than horizontal symmetry patterns. These results stand in marked contrast to previous research by demonstrating that the ability to process symmetrical relationships evolves early in perceptual development. There was a suggestion that subjects of all ages perceived information about the type of symmetry presented in the display, but there were agerelated differences in subjects' abilities to use this knowledge in constructing their responses. Additionally, analyses revealed no age-related biases toward imposing symmetrical responses on asymmetrical patterns.     

Identification of symmetry: Effects of stimulus orientation and head position

It has been argued that the perceptual advantage of symmetry depends upon the essentially symmetrical properties of the visual system. According to this explanation, the ease of identification of symmetries about different axes of orientation should decrease with increasing distance from the vertical: Reaction times to vertical symmetry should be faster than those to diagonal symmetry, which in turn should be faster than those to horizontal symmetry. Previous research demonstrating this pattern of responding employed stimuli with linear axes. In the present study, the subjects viewed tachistoscopically presented symmetrical and asymmetrical dot patterns (which had no explicit axes) in one of three head positions: upright, 45 deg left, and 45 deg right. The subjects’ performance failed to support the structural explanation: Identification of symmetry is equivalently fast for vertical and horizontal; vertical and horizontal show strong advantages over obliques, and this general advantage follows retinal coordinates. Findings are discussed in light of alternative theories of symmetry processing.     

The perceptual salience of symmetrical and asymmetrical sections of a line

A vertical line segment intersecting a horizontal one at different crossing points generates line sections. Visual perception of such line sections was investigated here in two experiments. In both experiments participants were most accurate and precise when they had to reproduce symmetrical sections. Interestingly, the different asymmetrical sections of a line were not equivalent in terms of participants' performance: constant errors changed as a function of sections and the error curve was nicely interpolated by the composition of two harmonics of the line length. In consistence with the harmonic fitting of the data, we propose that the perceptual salience of specific asymmetrical sections is a byproduct of the automatic triggering of a line midpoint identification process. Being perceptually tuned to symmetry warps our visual representation of the line, which results in systematic misperceptions. The way of bringing present and past experimental findings into a unitary whole is proposed.     

Perception of symmetry in infancy: the salience of vertical symmetry and the perception of pattern wholes

Four experiments were conducted to assess converging aspects of 4-month-old infants' perception of symmetry in visual patterns. Experiments 1 and 2 manipulated the structure and orientation of comparable patterns in order to evaluate the specialty of vertical symmetry. Infants showed no preference among vertically symmetrical, vertically repeated, and obliquely symmetrical patterns, but they processed vertically symmetrical patterns more efficiently than either vertically repeated patterns or obliquely symmetrical patterns. Experiment 3 manipulated the spatial separation of pattern components in order to determine the ability of young infants to integrate and coalesce information in visual patterns that is distributed in space. Infants processed vertically symmetrical patterns whose components were contiguous or nearly contiguous about the vertical axis (0 to 2.5 degrees separations) more efficiently than discontiguous patterns (5 and 10 degrees separations). Thus, extreme spatial separation about the vertical meridian caused infants to lose the advantage for vertical symmetry, and by inference their holistic perception of the visual pattern. Experiment 4 manipulated the organization of individual components of a vertical pattern in order to examine further infants' sensitivity to perceptual organization and synthesis of pattern form. Infants discriminated vertically symmetrical patterns from asymmetrical patterns with a vertical organization, thereby demonstrating sensitivity to the symmetrical organization of the pattern above their perception of components in the pattern. The results of these four experiments together corroborate and extend previous findings that vertical symmetry has a special status in early perceptual development and that infants can perceive pattern wholes.     

Incidental retrieval processes influence explicit test performance with data-limited cues

In two experiments, the influence of incidental retrieval processes on explicit test performance was tested. In Experiment 1, subjects studied words under four conditions (auditory-shallow, auditory-deep, visual-shallow, and visual-deep). One group of subjects received auditory and visual word-fragment completion; another group received auditory and visual word-fragment cued recall. Results indicated that changes in sensory modality between study and test reduced both recall and priming performances; levels of processing significantly affected only the cued recall test. These results indicated that incidental retrieval processes might affect explicit test performance when retrieval cues are data limited. Experiment 2 supported this conclusion by showing an effect of matching study and test modalities on explicit test performance with fragment but not with copy cues. Taken together, these results support Roediger and McDermott’s (1993) suggestion that explicit test performance is influenced by incidental retrieval processes when data-limited retrieval cues are used.     

Working memory and individual differences in the encoding of vertical, horizontal and diagonal symmetry

Previous studies, using a modified version of the sequential Corsi block task to examine the impact of symmetry on visuospatial memory, showed an advantage of vertical symmetry over non-symmetrical sequences, but no effect of horizontal or diagonal symmetry. The present four experiments investigated the mechanisms underlying the encoding of vertical, horizontal and diagonal configurations using simultaneous presentation and a dual-task paradigm. Results indicated that the recall of vertically symmetric arrays was always better than that of all other patterns and was not influenced by any of the concurrent tasks. Performance with horizontally or diagonally symmetrical patterns differed, with high performing participants showing little effect of concurrent tasks, while low performers were disrupted by concurrent visuospatial and executive tasks. A verbal interference had no effect on either group. Implications for processes involved in the encoding of symmetry are discussed, together with the crucial importance of individual differences.     

Memory loss versus memory distortion: The role of encoding and retrieval deficits in Korsakoff patients’ false memories

Recent studies with the Deese/Roediger-McDermott (DRM) paradigm have revealed that Korsakoff patients show reduced levels of false recognition and different patterns of false recall compared to controls. The present experiment examined whether this could be attributed to an encoding deficit, or rather to problems with explicitly retrieving thematic information at test. In a variation on the DRM paradigm, both patients and controls were presented with associative as well as categorised word lists, with the order of recall and recognition tests manipulated between-subjects. The results point to an important role for the automatic/controlled retrieval distinction: Korsakoff patients’ false memory was only diminished compared to controls’ when automatic or short-term memory processes could not be used to fulfil the task at hand. Hence, the patients’ explicit retrieval deficit appears to be crucial in explaining past and present data. Results are discussed in terms of fuzzy-trace and activation-monitoring theories.     

Squinting with the mind’s eye: Effects of stimulus resolution on imaginal and perceptual comparisons

Subjects either viewed or visualized arrays that were divided into four quadrants, with each quadrant containing a set of stripes. In two experiments, one array contained only relatively narrow (high-resolution) stripes, and one contained only relatively thick (low-resolution) stripes. The subjects compared sets of stripes in different quadrants according to their length, spacing, orientation, or width. When the subjects visualized the arrays, they required much more time to compare high-resolution patterns than low-resolution patterns; when the subjects saw the arrays, they evaluated both types of arrays equally easily. In addition, the results from the third experiment provide strong evidence that people use imagery in this task; in one condition, the subjects evaluated oblique sets of stripes, and in another condition, they evaluated vertical and horizontal stripes. In both imagery and perception, the subjects made more errors when evaluating oblique stimuli; in imagery, they also required more time to evaluate oblique stimuli. The results suggest that additional effort is required in imagery to represent visual patterns with high resolution. This finding demonstrates that, although imagery and perception may activate common brain regions, it is more difficult to represent high-resolution information in imagery than in perception.     

The effect of hemispatial neglect on the perception of centre

Highly variable bisection performance in neglect patients has been attributed to an increased 'zone of indifference'. The indifference zone indicates the discrepancy between two line lengths which are judged as equal in length. Following this argumentation, the central area of a line should be expanded in neglect patients. The present two experiments investigated for the first time the expansion of the central area using a modified version of the Landmark Task. The location of a central or asymmetrical bisection mark on a horizontal line had to be judged (centre/left/right). In both experiments neglect patients, unlike healthy and patient controls, showed clear deficits in judging the location of the mark correctly and tended to judge asymmetrical marks of up to 4 cm as centrally positioned. The results are in agreement with and provide the first clear evidence of an enlarged perceptual zone of indifference in patients with hemispatial visual neglect.     

Context superiority in a detection task with line-element stimuli: a low-level effect

Detection and identification performances for vertical and horizontal target elements embedded within an array of oriented noise elements were measured as a function of the orientation difference between the target and noise elements. Detection performances obtained with one vertical and three horizontal target elements clustered together and displayed such that they formed a schematic face-like pattern were significantly better than those obtained with the same clustered target elements displayed in an arbitrary, symmetrical or asymmetrical, configuration. This was so even though the identification of the face and nonface stimuli was well below the detection threshold of their parts. Detection thresholds for the clustered nonface patterns were slightly but significantly lower than those for the same target elements dispersed among the noise elements. Probability summation calculations based on the detection results obtained with one single target element predict detection thresholds which are intermediate between those of the clustered and dispersed targets, suggesting that inhibitory and facilitatory spatial interactions respectively are at work for the two types of stimuli. The existence of a context(face)-superiority effect at the detection level indicates top-down/bottom-up interactions between remote visual processing stages.     

Change of perspective in discourse comprehension: encoding and retrieval processes after brain injury

Damage to frontal areas has been associated with nonaphasic language disturbances in which word and sentence level processes remain largely intact but text level processes are impaired. Most studies providing evidence for these language deficits have concentrated on text production. To study text comprehension of nonaphasic patients, we adopted the paradigm of Anderson and Pichert (1978) that was developed to separate encoding from retrieval processes. Subjects read a story under one of two alternative perspectives and subsequently recalled it. After this first recall, they were instructed to now adopt the second perspective and to recall the story once more. Twenty-four brain-injured patients participated. Each patient's lesion was evaluated with respect to the involvement of right- and/or left-frontal regions. Seven patients showed unilateral left-frontal lesions, five patients unilateral right-frontal lesions, four patients had bilateral frontal damage, and the lesions of the remaining eight patients did not involve frontal areas. The only factor predicting behavioral results was the presence of a left-frontal lesion. For patients without frontal lesions and patients with unilateral right-frontal lesions, we replicated previously reported results. Encoding relevant information was recalled better than other information. Furthermore, the switch of perspective aided recall of perspective relevant information during the second recall. In contrast, patients with left-frontal or bilateral frontal lesions could not make use of the perspective instructions. While they showed comparable recall performance, as well as sensitivity to the relative ease of information, neither the encoding instructions nor the switch instructions had an impact on the recall patterns. These results suggest that left-frontal damage leads to an impairment of goal directed text processing skills.     

It Takes Two To Tango: Understanding and Acquiring Symmetrical Verbs

Children's ability to understand symmetrical verbs was investigated, along with adults' use of linguistic and visual cues to learn novel symmetrical verbs. Symmetrical verbs encode a relationship r between two entities such that X r Y entails Y r X. In Experiment 1, sixteen children (mean age 4;8) acted out two types of sentences with symmetrical and asymmetrical verbs. Eight adult judges viewed videotapes of the children's performance and tried to guess what sentence type was being enacted. Judges' performance was predicted(p < .05) by the verb type, symmetrical or asymmetrical. In Experiment 2, seventy-two adult subjects received visual and linguistic cues to the meanings of novel verbs. Both cue types affected subjects' judgments about whether the new verbs were symmetrical or asymmetrical (p < .05).     

注意控制与短时记忆的知觉组织

、考察了短时记忆中的知觉组织是否受双作业时指导语引导的注意策略控制。各有24名北京大学本科生参加了自由回忆和顺序回亿实验。实验任务有2种：记忆和声音监控。声音监控或者安排在记忆编码阶段,或者安排在记忆提取阶段。双作业时的指导语类型有3种,分别强调记忆、声音监控或两种作业同样重要。记忆项目表分2种：不分组和知觉分组。研究发现：自由回忆中的知觉组织仅受编码阶段的指导语影响;顺序回忆中的知觉组织仅受提取阶段的指导语影响。作者设想,短时记忆中的知觉组织在编码和提取阶段都受注意控制,但记忆类型不同,注意控制的作用地点和表现形式也有所不同。     

Developmental and individual differences in visual memory span

The effects of chronological age (5+, 7+, 10+, and adult), articulatory suppression and spatial ability were assessed on three measures (recognition memory, partial recall, and free recall) of visual memory span for patterns, using a procedure devised by Wilson, Scott & Power (1987). Although span increased into adulthood for all three tasks, concurrent articulatory suppression acted to reduce span for the 10-year-old and adult subjects. The ability to generate accurate visuo-spatial representations at retrieval is perfectly well developed by 7 years of age. Speed of response was lengthened for the youngest age group, but was immune to the effects of concurrent articulatory suppression. Good spatial ability was associated with higher span estimates on all tasks, regardless of age. Whilst the data support the existence of a system for representing visual patterns, which increases in capacity with increasing chronological age, the system (or processes accessing it at retrieval) is not immune to verbal recoding strategies. The independent association of spatial ability with span is taken to imply that nonverbal encoding and/or maintenance strategies can act to boost visual span from at least 5 years of age.     

Spatial recall improved by retrieval enactment

Evidence from studies of intentional learning suggests that the accuracy of recall is not assisted by appropriate enactment at retrieval, as opposed to encoding. In the present study, long-term recall of spatial arrays following incidental learning (text messaging or calculator use) was tested under three different motor conditions at retrieval. For both letter and number arrays, the accuracy of recall was found to be improved by relevant enactment at the time of retrieval, relative to retrieval with no movement. In contrast, irrelevant movement was found to produce an impairment in accuracy. The overall accuracy of recalling a letter array was found to be a power-law function of the frequency of exposure to the array. The findings are discussed in terms of the hypothesis that appropriate movement during memory retrieval recruits egocentric representations that supplement allocentric representations subserving longer term spatial recall.     

Vertical-horizontal illusion: One eye is better than two

The vertical-horizontal illusion is the tendency for observers to overestimate the length of a vertical line relative to a horizontal line that has the same length. One explanation of this illusion is that the visual field is elongated in the horizontal direction, and that the vertical-horizontal illusion is a kind of framing effect (Künnapas, 1957a, 1957b, 1957c). Since the monocular visual field is less asymmetric than the combined visual field, this theory predicts that the illusion should be reduced with monocular presentation. This prediction was tested in five experiments, in which the vertical-horizontal illusion was examined in a variety of situations—including observers seated upright versus reclined 90°, monocular presentation with the dominant versus the nondominant eye, viewing in the dark versus in the light, and viewing with asymmetrical frames of reference. The illusion was reliably reduced with monocular presentation under conditions that affected the asymmetry of the phenomenal visual field.     

Effect of skill level on recall of visually presented patterns of musical notes

Expertise effects in music were studied in a new task: the construction of mental representations from separate fragments. Groups of expert musicians and non-musicians were asked to recall note patterns presented visually note by note. Skill-level, musical well-formedness of the note patterns and presentation mode were varied. The musicians recalled note patterns better than the non-musicians, even though the presentation was visual and successive. Furthermore, only musicians' performance was affected by musical well-formedness of the note patterns when visual gestalt properties, verbal rehearsability, and familiarity of the stimuli were controlled. Musicians were also able to use letter names referring to notes as efficiently as visual notes, which indicates that the better recall of musicians cannot be explained by perceptual visual chunking. These results and the effect of skill level on the distribution of recall errors indicate that the ability to chunk incoming information into meaningful units does not require that complete familiar patterns are accessible to encoding processes, yet previous knowledge stored in long-term memory affects representation construction in working memory. The present method offers a new reliable tool, and its implications to the research on construction of representations and musical imagery are discussed.     

The effects of symmetry and contour on recognition memory in children

Children in prekindergarten, kindergarten, and second grade were tested on a delayed match-to-sample task using abstract visual patterns. The patterns varied both in type of visual organization (unstructured, diagonally symmetrical, vertically symmetrical, and horizontally symmetrical) and in amount of contour. Following the initial memory task, we attempted to train half of the children at each grade by directing their attention to axes of symmetry; the other half of the children received a control task. Subsequently, the subjects were given a second delayed match-to-sample test. On both pre- and post-training trials, structure influenced performance, especially in the two younger groups. Vertical and horizontal symmetry generally facilitated performance in the prekindergarteners, while all three types of symmetry facilitated performance in the kindergarteners. In addition, children generally responded more accurately to patterns with lower levels of contour. They also made more like-contour than unlike-contour confusions, indicating that quantitative aspects of patterns were encoded. Group differences suggested that both processing capacity and memory increase during the age range studied. Finally, there was no indication that training improved performance at any age.     

Working memory load differentially affects tip-of-the-tongue states and feeling-of-knowing judgments

Tip-of-the-tongue states (TOTs) are judgments of the likelihood of imminent retrieval for items currently not recalled, whereas feeling-of-knowing judgments (FOKs) are predictions of successful recognition for items not recalled. The assumption has been that similar metacognitive processes dictate these similar judgments. In Experiment 1, TOTs and FOKs were compared for general information questions. Participants remembered four digits (working memory load) during target retrieval for half of the questions, and there was no memory load for the other questions. Working memory did not affect recall but decreased the number of TOTs and increased FOKs. In Experiment 2, participants maintained six digits during retrieval. TOTs decreased in the working memory condition, but FOKs remained constant. Experiment 3 replicated the results of Experiment 2 while asking for FOKs for recall. In each of the first three experiments, positive metacognitive judgments also affected working memory performance, supporting the idea that working memory and metamemory use similar monitoring processes. In Experiment 4, visual working memory did not affect TOTs or FOKs. The data support a view that TOTs and FOKs are separable metacognitive entities.     

Coactivation, pop-out, and symmetry affect line discrimination

17 college students discriminated between vertical and horizontal target lines flanked by vertical and horizontal distractors. Large displays with 3.0-cm lines and small displays half this size were used. The distractors were positioned above and below the target or to the left and right of it, forming vertical and horizontal global orientations. The number of flankers sharing the target's orientation was varied. Vertical targets and small display sizes were processed more quickly. Speed of responding did not differ for the two global orientations. There was no advantage for target lines consistent with global orientation. The results were replicated in Exp. 2 with diagonal flankers. This supports an explanation using stimulus compatibility, since diagonal lines do not correspond to either of the response options and cannot induce a tendency to respond more to one target than another. Displays with multiple symmetry were responded to faster than those with a single symmetry which were faster than asymmetrical displays, supporting the idea that symmetrical axes parallel and perpendicular to the target orientation provide a facilitative frame of reference. Coactivation from same-oriented flankers, pop-out from differences in orientation, and symmetry all influenced responding in these patterns.