The development of perceived structure and attention: evidence from divided and selective attention tasks

Three experiments provide converging evidence for the view that both perceived structure and attention change during the elementary school years. Kindergarteners, second graders, and adults performed three speeded tasks: divided attention to conjunctions of features, selective attention to orthogonal dimensions and selective attention to correlated dimensions. The tasks were performed with sizes and shapes that were either spatially integrated or spatially separated. In the divided attention task, conjunctions were identified as quickly as single features with integrated stimuli at all ages, but conjunctions were identified more slowly than single features with separated stimuli by all age group. In the orthogonal dimensions task, interference was observed with integrated stimuli across ages, but the interference in adult performance was asymmetric. With separated stimuli, interference was gradually eliminated with increasing age. In correlated dimensions tasks, younger children showed a redundancy gain with integrated stimuli, but no gain was observed in the performances of the older subjects. With separated stimuli there was no redundancy gain at any age. These results were interpreted to mean that integrated stimuli are initially perceived as wholes by all subjects, but that features become more accessible with increasing age. Even so, attention remains constrained by stimulus structure. In contrast, separated stimuli are initially perceived as features at all ages, and the improvement in performance with increasing age is attributable to the increasing command of attentional resources that accompanies development. Our discussion of these findings focuses on three issues: multiple trends in perceptual development, the characteristics of an adequate theory of perceptual representation and processing, and a comparison of the separability hypothesis and other developmental accounts of perceptual development.     

Aging and goal-directed emotional attention: distraction reverses emotional biases

Previous findings reveal that older adults favor positive over negative stimuli in both memory and attention (for a review, see Mather & Carstensen, 2005). This study used eye tracking to investigate the role of cognitive control in older adults' selective visual attention. Younger and older adults viewed emotional-neutral and emotional-emotional pairs of faces and pictures while their gaze patterns were recorded under full or divided attention conditions. Replicating previous eye-tracking findings, older adults allocated less of their visual attention to negative stimuli in negative-neutral stimulus pairings in the full attention condition than younger adults did. However, as predicted by a cognitive-control-based account of the positivity effect in older adults' information processing tendencies (Mather & Knight, 2005), older adults' tendency to avoid negative stimuli was reversed in the divided attention condition. Compared with younger adults, older adults' limited attentional resources were more likely to be drawn to negative stimuli when they were distracted. These findings indicate that emotional goals can have unintended consequences when cognitive control mechanisms are not fully available.     

Perceptual sensitivity to dimensional and similarity relations in free and rule-governed classifications

Two experiments were conducted to investigate the perceptual primacy of dimensional and similarity relations in the stimulus classifications of younger and older subjects. In Experiment 1, 4- and 10-year-olds were given free classifications in which they could group stimuli according to overall similarity or identities in size, color, or orientation. Both age groups classified stimuli most frequently according to identities on separate dimensions. In Experiment 2, 4-year-olds and adults were given free classifications followed by rule-governed classifications which required them to group stimuli according to specific relations. In the free classifications, a majority of subjects in both age groups classified the stimuli most frequently according to identities on separate dimensions. In the rule-governed classifications, both age groups were more accurate when a single separate relation was required for solution than when overall similarity was required. These results support a differential-sensitivity view of perceptual development, which asserts that individuals at all ages primarily perceive and use separate relations.     

多感觉整合中的声音诱发闪光错觉效应

声音诱发闪光错觉效应是典型的视听整合错觉现象, 是指当视觉闪光刺激与间隔100 ms内的听觉声音刺激不等数量呈现时, 被试知觉视觉闪光的数量与听觉声音的数量相等。声音诱发闪光错觉的影响因素既包括自下而上和自上而下的被试内差异因素, 也包括视听刺激依赖程度、视听整合的发展和视听刺激知觉敏感性等被试间差异因素。该效应的产生在时程上主要体现在早期加工阶段, 在脑区上主要涉及多处皮层及皮层下相关脑区。未来研究应进一步考察注意、奖赏和视听整合方式等认知加工对声音诱发闪光错觉的影响, 同时也应该关注声音诱发闪光错觉对记忆和学习的影响以及结合计算模型和神经科学的手段进一步探讨其认知神经机制。     

The effect of children's spontaneous cognitive sets on discrimination learning

Two experiments investigated the role of children's spontaneous cognitive “sets” in pictorial discrimination learning. Lists were constructed to highlight either perceptual or conceptual similarities among the stimuli. In each experiment age by treatment interactions revealed that in comparison to the behavior of older children (sixth graders), that of younger children (kindergartners) is governed more by the perceptible than by the conceptual attributes of stimuli—data in complete accord with Bruner's view of cognitive development.     

New-born infants' perception of similarities and differences between two- and three-dimensional stimuli

The new-born baby' ability to detect similarities and differences between three-dimensional stimuli and their two-dimensional representations is investigated in three experiments, using both visual preference and habituation procedures. In Expt 1 new-borns strongly preferred (looked more at) complex objects to their photographs. This preference was found with monocular viewing, and suggests that motion parallax is a salient cue in the detection of the differences between the two- and three-dimensional stimuli. The results from Expt 2 support the view that, for the new-born, the differences between objects and their two-dimensional representations are more detectable or salient than their similarities. These conclusions were further supported by the results from the last experiment, using simpler stimuli, although the preference was for the two- rather than the three-dimensional stimuli. The results suggest that studies which use only two-dimensional stimuli may provide only limited information about the course of perceptual development, at least in the first few months from birth.     

Children's perceptions of the effectiveness of techniques to reduce fear from mass media

In two separate studies, children reported on their perceptions of the effectiveness of various strategies for reducing fright reactions to mass media stimuli. Three age groups were involved: preschool, 3 to 5 years; early elementary school, 6 to 7 years; and older elementary school, 9 to 11 years. The studies revealed that the perceived effectiveness of cognitive strategies, such as “tell yourself it's not real,” increased with age, whereas that of noncognitive strategies, such as “get something to eat or drink,” decreased with age. The differential effectiveness of the two types of strategies had been predicted on the basis of cognitive developmental differences among the groups. Specifically, developmental increases were assumed in the ability to distinguish fantasy from reality, in the ability to modify one's own thought processes, and in functional cognitive capacity. Methodological differences between Study 1 and Study 2 demonstrated that younger children's “yea-saying” tendencies can be circumvented by employing forced choices between pairs of alternative strategies. Both studies also revealed that scary television shows and movies are quite popular among children and that fright reactions to such offerings are prevalent.     

Physical and cognitive dimensions in stimulus comparison

Two experiments were carried out using a same-different task with sets of four stimuli varying orthogonally in three dimensions. Sameness was defined by each of the three dimensions in turn, as well as by physical identity. Two types of dimensions, physical and cognitive, were studied. In Experiment 1, the numerals 6, 10, VI, and X, which vary in Length, System, and Name, were used. With simultaneous presentation, order of difficulty was from the physical dimension of Length to the cognitive dimension of Name. While overall difficulty was related to dimensional discriminability, internal evidence suggested that Name was not a dimension in the same sense as Length is, and that some stimulus pairs were simply easier to process than others, regardless of the response required (e.g., short stimulus pairs and Arabic numerals). With sequential presentation, Name was processed as fast as System, due largely to the fact that much faster responding occurred when an Arabic numeral was the second stimulus. Thus, with sequential presentation, Name provides a processing mechanism not provided by physical dimensions. In Experiment 2, the numerals 3, 4, 6, and 7, which vary in Magnitude, Oddness, and Curvilinearity, were used. The cognitive dimension of Magnitude was pro cessed most rapidly, and numerical distance between pairs of numbers dominated the results for “same” responses, regardless of the sameness rule used. Again, evidence was found for fast processing of some stimulus pairs (e.g., 3 4), regardless of the response required. Overall, these experiments are interpreted as indicating that cognitive factors such as stimulus familiarity may override aspects of physical discriminability with many dimensions and stimuli, that, even though a cognitive dimension can be used to generate a logically proper set of stimuli, it does not necessarily act as other, more physical dimensions do, and that clarification of the functional role of a dimension is more important than attempts to locate stages.     

Inhibition and aging: similarities between younger and older adults as revealed by the processing of unattended auditory information

The ability to selectively attend to an auditory stimulus appears to decline with age and may result from losses in the ability to inhibit the processing of irrelevant stimuli (i.e., the inhibitory deficit hypothesis; L. Hasher & R. T. Zacks, 1988). It is also possible that declines in the ability to selectively attend are a result of age-related hearing losses. Three experiments examined whether older and younger adults differed in their ability to inhibit the processing of distracting stimuli when the listening situation was adjusted to correct for individual differences in hearing. In all 3 experiments, younger and older adults were equally affected by irrelevant stimuli, unattended stimuli, or both. The implications for auditory attention research and for possible differences between auditory and visual processing are discussed.     

儿童与成人对社会和非社会正性情绪刺激脑电反应特征比较

采用事件相关电位技术探究不同年龄群体社会与非社会正性情绪刺激加工是否具有差异。研究发现：在P2成分上,成人在情绪刺激下诱发的波幅大于儿童;N2成分上,儿童在三种情绪刺激条件下波幅无显著差异。成人在社会性情绪刺激条件下诱发的脑电波幅大于在中性情绪刺激条件和非社会情绪刺激条件下诱发波幅;在LPP早、中、晚时间窗中,儿童的LPP波幅大于成人。由此,儿童与成人在社会和非社会正性情绪刺激加工上存在明显差异。     

Similarity relations among synesthetic stimuli and their attributes

Four experiments examined the similarity relations that exist among bimodal attributes that correspond synesthetically (e.g., white color and high pitch) and among stimuli formed by combining these attributes either congruently (e.g., white/high, black/low) or incongruently (e.g., white/low, black/high). Previous research suggests two hypotheses: (a) Synesthetic stimuli are compared as wholes on the basis of their overall similarity, and (b) nonidentical congruent stimuli are more dissimilar than nonidentical incongruent stimuli. In these four experiments, similarity among either individual attributes (Experiments 1 and 4) or bimodal stimuli (Experiments 2 and 3) was measured by either ratings or response latencies; similarity judgments were scaled with an individual differences scaling procedure (SINDSCAL). Stimulus comparisons were fit well by a Euclidean but not a city-block metric, supporting the overall similarity hypothesis. However, there was little evidence that subjects perceived congruity/incongruity among stimulus wholes, even though subjects were sensitive to correspondence/noncorrespondence among attributes. These results were replicated in four additional experiments using larger stimulus sets. A two-process account is proposed in which stimulus formation (intersensory processing) occurs independently of the abstraction of cross-sensory meaning (figurative processing).     

The depth and selectivity of suppression in binocular rivalry

Binocular rivalry occurs when the two eyes are presented with incompatible stimuli and the perceived image alternates between the two stimuli. The aim of this study was to find out whether the periodic perceptual loss of a monocular stimulus during binocular rivalry is mirrored by a comparable loss of contrast sensitivity. We presented brief test stimuli to one eye while its conditioning stimulus was dominant or suppressed. The test stimuli were varied widely across four stimulus domains--namely, the relative stimulation of medium- and long-wavelength-sensitive cones, duration, spatial frequency, and grating orientation. The result in each case was the same. Suppression depended slightly or not at all on the type of test stimulus, and contrast sensitivity during suppression was around 64% of that during dominance. The effect of suppression on sensitivity is therefore very weak, relative to its effect on the perceived image. Furthermore, suppression was largely independent of the similarity between the conditioning and the test stimuli, indicating that our results are better explained by eye suppression than by stimulus suppression. A model is presented to account for the small, monocular sensitivity loss during suppression: It assumes that test detection precedes conditioning stimulus perception in the visual pathway.     

Does switching between strategies within the same task involve a cost?

In two experiments, participants had to switch regularly between two cognitive strategies of a different complexity in the context of a numerosity judgement task. Expt 1 comprised bivalent stimuli (i.e. allowing the application of the two strategies), whereas Expt 2 involved univalent stimuli (i.e. allowing the application of only one strategy). Both experiments revealed that switching between strategies entailed a cognitive cost that was reflected in longer response times on switch compared to non‐switch trials but not in reduced accuracy. The size of this switch cost did not differ as a function of strategy complexity but tended to diminish as a strategy became more appropriate for solving a particular problem. We discuss the extent to which current theories of task switching can account for these findings.     

Faces, flowers and football boots: capacity limits in distractor processing

While visual attention can be attracted by task-irrelevant stimuli, questions remain regarding how many irrelevant items can be processed simultaneously and whether capacity limits are equivalent for all types of stimuli. To explore these issues, participants were required to classify verbal stimuli that were flanked by either one or two response-matching or response-mismatching faces (Expts. 1 and 2) or objects (Expt. 2). The results revealed that when stimulus categorization was sufficient to trigger flanker interference, distractor processing was insensitive to the number of irrelevant stimuli. When, however, stimulus identification was needed to drive flanker interference, distractor processing was attenuated when two task-irrelevant items were presented. The theoretical implications of these findings are considered.     

Statistical learning within and between modalities: pitting abstract against stimulus-specific representations

When learners encode sequential patterns and generalize their knowledge to novel instances, are they relying on abstract or stimulus-specific representations? Research on artificial grammar learning (AGL) has shown transfer of learning from one stimulus set to another, and such findings have encouraged the view that statistical learning is mediated by abstract representations that are independent of the sense modality or perceptual features of the stimuli. Using a novel modification of the standard AGL paradigm, we obtained data to the contrary. These experiments pitted abstract processing against stimulus-specific learning. The findings show that statistical learning results in knowledge that is stimulus-specific rather than abstract. They show furthermore that learning can proceed in parallel for multiple input streams along separate perceptual dimensions or sense modalities. We conclude that learning sequential structure and generalizing to novel stimuli inherently involve learning mechanisms that are closely tied to the perceptual characteristics of the input.     

Age-related differences in recognition memory: effects of materials and context change

The study explored age-related differences in the effects of context change on recognition memory by presenting object names (Expt. 1A) or their pictures (Expt. 1B) on background scenes. Participants later attempted to recognize previously presented items on background scenes that were original, switched, blank, or new. Older adults recognized fewer word stimuli than did younger adults, and context effects were larger for older adults. With pictures, however, the age-related decrement was eliminated and context effects were reduced. The beneficial effect of context reinstatement in older adults occurs despite the finding that they are less able to recall or recognize such contexts (Experiment 2). Older adults can use context information in recognition memory at least as efficiently as younger adults when suitable materials and conditions are provided.     

Partial awareness creates the "illusion" of subliminal semantic priming

We argue that the lack of consensus regarding the existence of subliminal semantic processing arises from not taking into account the fact that linguistic stimuli are represented across several processing levels (features, letters, word form) that can independently reach or not reach awareness. Using masked words, we constructed conditions in which participants were aware of some letters or fragments of a word, while remaining unaware of the whole word. Three experiments using the Stroop priming paradigm show that when the stimulus set is reduced and participants are encouraged to guess the identity of the prime, such partially perceived stimuli can nonetheless give rise to "semantic" processing. We provide evidence that this effect is due to illusory reconstruction of the incompletely perceived stimulus, followed by usual semantic processing of the result. We conclude that previously reported unconscious Stroop priming is in fact a conscious effect, but applied to a perceptual illusion.     

奖赏刺激的脑电反应特征跨文化差异:一个ERP研究

本研究从文化--社会神经科学的角度出发,采用事件相关电位的方法来探究不同文化背景下的个体对具有进化和社会文化代表性的正性刺激—奖赏刺激的脑电反应特征是否具有差异。本研究采用the Door Task实验范式考察了26名中国人和24名高加索白人对不同反馈反应的脑电特征跨文化差异。结果显示,负性反馈条件下诱发的FRN平均波幅比正性反馈条件诱发的平均脑电波幅更负,这种正负反馈的波幅差异只在中国被试中有体现。在P3成分上,在正性反馈条件下,中国被试诱发的脑电波幅大于西方被试,负性反馈条件下,两组无显著差异。研究结果表明,相对于西方被试,中国被试对奖赏反馈刺激可能具有较高的敏感性。这说明中西方文化下的个体对正负性反馈刺激的加工的脑电反应特征存在显著的差异。     

"Perceptual scotomas": a functional account of motion-induced blindness

ABSTRACT— In motion-induced blindness (MIB), salient objects in full view can repeatedly fluctuate into and out of conscious awareness when superimposed onto certain global moving patterns. Here we suggest a new account of this striking phenomenon: Rather than being a failure of visual processing, MIB may be a functional product of the visual system's attempt to separate distal stimuli from artifacts of damage to the visual system itself. When a small object is invariant despite changes that are occurring to a global region of the surrounding visual field, the visual system may discount that stimulus as akin to a scotoma, and may thus expunge it from awareness. We describe three experiments demonstrating new phenomena predicted by this account and discuss how it can also explain several previous results.     

Internationally adopted children’s cognitive and social-emotional development during the first post-adoption year: A longitudinal study

Research is consistent in showing that international adoption is an intervention leading to great recovery for adopted children, but there is a need of research on factors associated with recovery. The present study is aimed at: (a) assessing children’s cognitive skills and social-emotional dimensions on their arrival to their new family; (b) evaluating their development after one year; (c) identifying which factors influence development, taking into account children’s gender, age, health status on arrival, years of institutionalization, and the initial psychological delay. Participants were 53 internationally adopted children (30 boys and 23 girls), aged 5.68 years old on average at placement (range 2–14). Results showed that children’s development one year after adoption was extraordinary, both in cognitive skills and in social-emotional dimensions. The children more delayed on arrival showed the larger progress over time, and their recovery was greater in cognitive skills than in social-emotional dimensions.