Individual pattern representations are context independent, but their collective representation is context dependent.

We studied context dependency of the representations underlying perceptual "goodness". Three experiments used a same-different task with classical Garner 5-dot patterns presented with an interstimulus interval (ISI) of 500 ms. Same patterns were allowed to be rotated or reflected versions of each other. Pattern goodness was varied according to rotation and reflection equivalence, using Garner's equivalence set size (ESS) measure. The ESS of both first and second patterns affected reaction time and accuracy. A model based on assumptions that Garner's equivalence sets constitute the generic representation of these patterns and that items within these sets are accessed serially was fitted to the data. Excellent fits were obtained, which were robust against frequency-induced bias at the level of the individual pattern, but sensitive to such bias at the level of the equivalence set. It was concluded that individual pattern representations are context independent, whereas their collective representations are context dependent. Simplicity and likelihood principles, therefore, seem to apply to different levels of a representation hierarchy.     

Task-invariant aspects of goodness in perceptual representation.

In two experiments, pairs of Garner's classical 5-dot patterns were presented with an interstimulus interval of 500 ms in a same-different task in which a physical sameness criterion was used: Rotated or reflected versions of the same pattern were rated as different. Patterns varied in "goodness" according to Garner's equivalence set size measure. Both first and second pattern goodness affected reaction time and accuracy. This result and fits of models to reaction time data indicate that equivalence set representations are used in the task, as in a related categorical matching task in previous studies. Two effects were observed that contrast with the categorical matching task: One is a conflict between the need to respond different to patterns that are categorically equivalent under the equivalence set representation; the other is that extra time is needed for rechecking of the representation if pattern structures are hard to distinguish. In combination with previous studies, the present results show that even though the processes differ, the same representational mechanism is used across tasks.     

Does size rescaling require central attention?

The goal of the present experiment was to determine if object size rescaling in the shape-matching task requires central resources. Two polygons were presented side by side as the second task in a psychological refractory period paradigm. The polygons could be the same as each other or mirror images of each other and the size ratio between the two polygons was varied. In the first task, subjects were required to make a speeded response to the pitch of a tone. The polygon task followed at varying SOAs and the subjects then made a speeded same/mirror image judgement on the polygons. The size ratio effect was additive with SOA indicating that size rescaling is capacity demanding and that it requires central attention.     

All-or-none bottleneck versus capacity sharing accounts of the psychological refractory period phenomenon

The goal of the present experiment was to test the predictions of Central Bottleneck and Central Capacity Sharing models. According to the Central Bottleneck model, dual task interference, as observed in the PRP paradigm, is caused by an all-or-none bottleneck in information processing. The Central Capacity Sharing model postulates that dual task interference is caused by a capacity limited process that can allocate capacity in a graded fashion. The Central Bottleneck model predicts no change in RT1 with decreasing SOA, whereas the Central Capacity Sharing model predicts that RT1 will increase with decreasing SOA and that the slope of the RT1 SOA effect will depend upon the difficulty of task 2. Subjects were required to perform a tone pitch judgement and shape-matching task in rapid succession. Task order was randomized and the SOA between the first and second stimulus varied from 50 to 1250 ms. Results from this experiment favour the Central Capacity Sharing model. The results were then run through simulations of both the Central Bottleneck and Central Capacity Sharing models. Results from the simulations also favoured the Central Capacity Sharing model. As the difficulty of the second task increased, more capacity was allocated to it, confirming the prediction that as task 2 difficulty increases, the RT1 SOA slope increases. The proportion of capacity allocated to the first task varied from.78 to.91 indicating that capacity can be allocated in a graded fashion.     

注意瞬脱范式中的知觉负载对情绪面孔加工的影响

情绪性刺激的加工是否受注意影响目前尚存争论。基于许多操纵空间注意焦点的研究未能在注意资源的分配上进行精确的调节, 本实验将时间维度的注意瞬脱范式与负载理论相结合, 通过调节注意瞬脱中T1刺激物知觉负载水平的高低(箭头朝向相同与否), 观察被试在四种时间延迟条件下(延迟2, 延迟3, 延迟5, 延迟8)T2目标侦测任务恐惧和中性面孔的反应正确率, 从而对情绪性刺激的加工特征进行研究。实验发现：对恐惧面孔侦测的正确率在高知觉负载条件下显著降低, 而中性面孔则不受知觉负载水平影响, 并且这种高知觉负载对恐惧面孔加工的抑制作用仅发生在注意瞬脱中的短延迟条件下。说明在知觉加工资源和注意调节作用同时受限的情况下恐惧面孔的优势加工受到限制, 提示情绪性刺激的加工与中性刺激相比消耗的加工资源较少, 并依赖于注意的调控。     

注意力资源限制与双任务的相互干扰机制

采用心理不应期研究范式, 两个反应时实验检测了注意力资源分配的特征以及双任务的相互干扰机制。每次实验中, 要求被试快速、相继对高低音辨别任务(T1)和Stroop任务(T2)作出选择性反应, T1和T2间采用6种不同的时间间隔(SOA), 以系统考察不同SOA条件下两个任务的反应时走势。结果发现：(1) 在重叠的双任务情境中, T1的中枢加工导致在T2上出现显著的PRP效应, T2的中枢反应选择对T1的反应选择和反应执行加工同样产生显著的影响。SOA以及T2的难度与复杂度实质性地影响了T1的反应选择和反应执行加工。(2) 当两个任务同时需要进行中枢反应选择加工时, 一个任务占用更多的注意资源将导致另一任务获得较少的注意资源, 注意资源量的多寡直接决定了该任务的加工效率。(3) 两个任务的加工相互影响、相互制约, 这种制约机制不仅仅存在于中枢反应选择阶段, 在反应执行阶段仍然存在。     

Differentiation of holistic processing in the time course of letter recognition

Pairs of letters, pseudo-letters, and basic geometrical shapes were presented in a sequential same-different task, in which the time between the first and second items was varied. The second item was either presented in isolation or surrounded by an irrelevant geometrical shape that could be congruent or incongruent to the target. Congruence effects were obtained for shapes and pseudo-letters, but not for letters if the interval between the first and second items was short. Absence of congruence effects was interpreted, in accordance with earlier findings, as categorical influence on early visual integration processes; letters are processed less holistically than non-letter shapes. The present result indicates that categorical influence of letters depends on the time course of stimulus processing. As a highly automatized process, it is effective for stimuli appearing at a relatively fast rate, whereas, a slower rate of stimulus presentation eliminates task-irrelevant categorical influences.     

A PRP-study to determine the locus of target priming effects

Visual stimuli that are made invisible by a following mask can nonetheless affect motor responses. To localize the origin of these target priming effects we used the psychological refractory period paradigm. Participants classified tones as high or low, and responded to the position of a visual target that was preceded by a prime. The stimulus onset asynchrony (SOA) between both tasks varied. In Experiment 1 the tone task was followed by the position task and SOA dependent target priming effects were observed. When the visual position task preceded the tone task in Experiment 2, with short SOA the priming effect propagated entirely to the tone task yielding faster responses to tones on visually congruent trials and delayed responses to tones on visually incongruent trials. Together, results suggest that target priming effects arise from processing before and at the level of the central bottleneck such as sensory analysis and response selection.     

客体工作记忆的保持对时距知觉的影响

初步探讨毫秒范围内,客体信息保持对时间知觉的影响。实验一发现,知觉到的时间不受记忆负荷的影响,但当保持时间短时,低负荷的反应时低于高负荷的反应时;实验二仅要求被试完成时间知觉任务,发现知觉负荷异于记忆负荷对时间知觉的影响。结果说明,客体工作记忆保持对时间知觉的影响受到工作记忆资源的调节。     

Representational economy, not processing speed, determines preferred processing strategy of visual patterns

According to Garner, visual patterns are mentally represented as categories rather than by their physical identity. On the other hand, physical and categorical identification tasks engender their own specific processing strategies. Nevertheless, categorical strategies should be more generic than physical ones. We tested this prediction using Garner patterns in a same-different task: one version involved categorical, the other physical identification. Both tasks showed effects of categorical representation but also contrasting categorical and physical processing strategies in their response time profiles. When trials from categorical and physical identification tasks were randomly intermixed, mixing costs were additive for categorical trials but not for physical trials, indicating a shift in processing strategy for the latter. For these trials, the physical response time profile was found to be displaced by a categorical profile. We concluded that the more generic processing strategy is the one that maximizes the role of categorical representation.     

Dissociations and dependencies between speed and accuracy: Evidence for a two-component theory of divided attention in simple tasks

Previous work has amply demonstrated divided attention “costs” both in single-task multistimulus visual processing and in performance of multiple simple tasks; however, the relationship between the two has not been clarified. This article postulates two distinct causes: (1) visual processes that commence without delays and proceed simultaneously, but show lingering mutual interference dependent upon complexity, and (2) discrete queueing of the response selection stage. The first has resource-like properties, while the second has bottleneck-like properties. Either or both can generate performance costs observed in any particular situation, accounting for a variety of previous results. To test this theory, the effects of stimulus onset asynchrony (SOA) on accuracy and speed in performing dual choice tasks were examined. The first two experiments involved a choice response to a tone as a first task, and a second task requiring complex perceptual decisions (digit identification or conjunction search) with masked displays and unspeeded second responses. Reducing the SOA had negligible effects upon second-task accuracy, and performance in the two tasks was virtually independent. However, when speeded manual (Exp. 3) or vocal (Exp. 4) responses were required on the same second task, dramatic interference was observed, with strong positive dependencies between reaction times (RTs) on the two tasks. When both tasks involved complex visual displays, SOA reductions produced dramatic interference, but no dependencies between performance, whether the first task involved a speeded (Exp. 5) or unspeeded (Exp. 6) response. The results reject pure late-selection accounts and general capacity sharing models, and support the two-component theory. They also suggest that standard use of the term “attention,” suggesting a single resource or mechanism, is highly misleading.     

Stimulus-specific processing consequences of pattern goodness

Two issues concerning the effects of visual pattern goodness on information processing time were investigated: the role of memory vs. encoding and the role of individual stimulus goodness vs. stimulus similarity. A sequential “same-different” task was used to provide differentiation of target item or memory effects from display item or encoding effects. Experiment 1 used four alternative stimuli in each block of trials. The results showed that good patterns were processed faster than poor patterns for both “same” and “different” responses. Furthermore, the goodness of the target item had a greater effect on reaction time than did the goodness of the display item, indicating that memory is more important than encoding in producing faster processing of good stimuli. Effects of interstimulus similarity on processing time were minimal, although isolation of good stimuli in a similarity space could explain many of the results. Experiment 2 replicated the results of Experiment 1, despite the fact that differences in similarity space had been minimized by using only two alternative stimuli in each block. In addition, the speed of processing a “same” pair was essentially independent of the particular alternative stimulus in a block. These results suggest that in this task, there is a processing advantage for good stimuli that is stimulus specific, with the effect operating primarily in memory.     

The Eriksen flanker effect revisited.

Four studies are reported on the potential role of perceptual interference in a standard Eriksen flanker task. In the first study, incongruent flanker letters showed the usual effect on choice reaction time (CRT) to the target letter but had no effect on the visual fixation time (VFT) needed to distinguish target and flankers. In the second experiment, the effect of incongruent flankers was studied in the context of a same-different response in regard to the target letter and a subsequently presented single letter. The effect of incongruent flankers vanished at an interstimulus interval of 200 ms. In Experiment 3, the same-different task was used in the paradigm of the functional visual field with a target-flankers combination as stimulus on the left (SL) and a single letter as stimulus on the right side (SR) of the visual field. Flankers did neither affect VFT nor the same-different CRT suggesting that target selection may proceed during the saccade from SL to SR. In Experiment 4 effects were studied of flanker-to-target and target-to-single-letter similarity. Flanker-to-target similarity did neither affect VFT nor same-different CRT but target-to-single-letter similarity prolonged same-different CRT. Together, the results suggest parallel perceptual processing of target and flankers, followed by competition of responses to the target and to the incongruent flankers. In line with earlier research, processes of response selection and response competition appear not to be tied to VFT but to proceed in parallel with the saccade from SL to SR.     

Temporal integration of vibrotactile patterns

Three experiments were conducted to measure the temporal integration of vibrotactile patterns presented to the fingertip. In Experiment 1, letters were divided in half and the time between the onsets of the first half of the letter and second half of the letter, stimulus onset asynchrony (SOA), was varied. The recognizability of the letters declined as the SOA was increased from 9 to 100 msec. In Experiment 2, the time between two patterns constituting a masking stimulus was varied and the stimulus effectiveness in interfering with letter recognition was determined. The amount of masking increased as the SOA increased from 9 to 50 msec. In Experiment 3, the SOA between a letter and its complement (the portions of the tactile array not activated by the letter) was varied. Increasing SOA from 9 to approximately 50 msec led to increasingly accurate letter recognition. The results of the three experiments suggest that the skin is capable of complete temporal integration over a time period of less than 10 msec, and that the temporal integration function becomes asymptotic in 50 to 100 msec. The results also suggest that the onset of a vibrotactile pattern is critical for generating contours. The implications of the results for modes of generating tactile patterns and for temporal masking functions are discussed.     

Units of word recognition: Evidence for the use of multiple units

The present experiments were concerned with subsyllabic units in word recognition. The studies employed a same-different RT task. A one-syllable word and a probe were presented simultaneously, and subjects responded “same” if the probe was an integral subset of the word (BLAST:BL), and “different” otherwise (BLAST:BC). Probes included single letters (BLAST:L), doublets (BLAST:LA), triplets (BLAST:LAS), and the whole word (BLAST: BLAST). The first experiment suggested that a variety of spelling patterns, as well as the whole word, served as units of processing. In particular, initial consonant clusters were processed as quickly as single letters, and only slightly faster than the whole words. Consonant strings were used in the second experiment, which demonstrated spelling pattern effects with permissible strings (BLGST:BL) as compared to nonpermissable strings (BXJPK:BX). A third experiment demonstrated that the particular effective units depend on task demands.     

Relationship between flanker identifiability and compatibility effect

What is the relation between the identifiability of masked flankers and their ability to induce compatibility effects in a letter classification task? Using a within-subjects design (n=8), we first determined identification performance for two flankers (H or N) around an irrelevant target letter as a function of the time (stimulus onset asynchrony, or SOA) after which the flankers were masked. In a second condition, subjects classified the central letter of the same stimulus patterns irrespectively of the identity of the flankers. The compatibility effects increased with increasing identification performance as a function of SOA, and we found a significant compatibility effect even at an SOA at which the identifiability of the flankers did not differ significantly from zero. We discuss the statistical power of our design and an interpretation of our results in terms of a dissociation between perceptual processes and processes directly activating the motor system (direct parameter specification; cf. Neumann, 1990).     

Garner and congruence effects in the speeded classification of bimodal signals

The role of attention in speeded Garner classification of concurrently presented auditory and visual signals was examined in 4 experiments. Within-trial interference (i.e., congruence effects) occurred regardless of the attentional demands of the task. Between-trials interference (i.e., Garner interference) occurred only under conditions of divided attention when making judgments about auditory signals. Of importance, the data show congruence effects in the absence of Garner interference. Such a pattern has been rarely reported in studies of the classification of purely visual stimuli and contradicts theoretical accounts asserting that the effects share a common locus. The data question the notion that Garner classification reveals fundamental insights about the nature of the perceptual processing of bimodal stimuli.     

双任务情境下心理旋转的并行加工机制

采用心理不应期研究范式,三个反应时实验检测了心理旋转任务和其他认知操作任务能否并行加工的问题。在每个实验中要求被试快速、系列地完成对高低音的辨别任务(T1)和不同旋转角度的正反像辨别任务(T2),T1和T2呈现的时间间隔运用变化的SOA。结果发现：(1)T1的反应选择对T2的反应选择产生了很大的影响,在T2上PRP效应显著。心理旋转的操作成绩随着SOA的缩短而降低。(2)在T1上同样存在随着SOA缩短,反应时增加,正确率下降的趋势。T2的反应选择对T1的反应选择同样产生了显著的影响。(3)T2的反应选择对T1的中枢加工产生了相应的影响,表明当T1的反应选择占据中枢瓶颈时,心理旋转任务和其他认知操作任务在中枢瓶颈中并行得到了有效的加工     

Shifting visual attention and selecting motor responses: distinct attentional mechanisms.

Does shifting visual attention require the same central mechanism as that required for selecting overt motor responses? In Experiment 1, Ss performed 2 tasks: a speeded manual response to a tone and an unspeeded report of a cued target letter in a brief masked array. Stimulus onset asynchrony (SOA) between tone and array was varied. If the attention shift to the target was delayed by the first task, then there should be more second-task errors at short SOAs and on trials with slow first-task responses. In fact, SOA effects and dependencies were minimal. Results were unchanged in further experiments in which the relation between cue and target was symbolic, spatially "unnatural," or based on the color of the target. Two additional experiments validated key assumptions of the method. The results confirm that although selection of motor responses constitutes a processing bottleneck, the control of visual attention operates independently of this bottleneck.     

Temporal integration and vibrotactile backward masking

Subjects were presented with vibrotactile target patterns to their left index fingertips. The target patterns varied in the number of line segments that they contained and were presented in the presence or absence of a backward-masking stimulus. The stimulus onset asynchrony (SOA) between the target and masker was varied. In an identification task, subjects' errors indicated that the effect of the masker at brief SOAs was to increase the perceived number of line segments in the target. This effect diminished with increasing SOA, and at the longest SOAs subjects confused targets with patterns containing the same number of line segments but varying in how the line segments were related. In an estimation task, the effect of the masker was to increase the number of line segments estimated to be contained in the target pattern. The effect of the masker at brief SOAs is discussed in terms of an integration theory of vibrotactile backward masking. At longer SOAs, the results suggest that the masker may interfere with the extraction of relational information in the target pattern.