Attention mechanisms for multi-location first- and second-order motion perception

Lü, Zhong-Lin; Liu, Christine Qi; Dosher, Barbara Anne

doi:10.1016/s0042-6989(99)00172-8

Cited by 61 publications

(55 citation statements)

References 50 publications

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“…Pure cases of stimulus enhancement (Lu and Dosher, 1998;Lu, Liu, and Dosher, 2000) and external noise exclusion (Dosher and Lu, 2000a;Dosher and Lu, 2000b;Lu, Lesmes, and Dosher, 2002) have been documented in different situations as the mechanism of location-cued visual attention. Pure external noise exclusion (see Fig.…”

Section: Empirical Results and Taxonomy Of Mechanisms Of Spatialmentioning

confidence: 99%

External Noise Distinguishes Mechanisms of Attention

Lü¹,

Dosher²

2005

Neurobiology of Attention

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Attention to objects or features of objects affects performance on perceptual tasks such as detection, recognition, or identification. The speed or accuracy of task performance can be significantly influenced by changes in the state of attention, especially in complex task environments. The state of attention may be manipulated by specific environmental cues, or by decisions about allocation of attention induced by task demands. The challenge is to understand and predict these attention-mediated changes in task performance, and to identify the mechanisms by which attention is operating. A theoretical and empirical framework has been developed to directly assess the mechanisms of attention by systematically manipulating the amount and/or characteristics of the external noise added to the signal stimuli and measuring modulations of perceptual discriminability (signal and noise levels) in the cognitive processes. Three classes of attention mechanisms-stimulus enhancement, external noise exclusion, and internal noise reduction, each with its signature performance pattern, can be distinguished. Empirically, the two mechanisms of stimulus enhancement and external noise exclusion are shown to occur in different circumstances. A task-taxonomy of attention mechanisms is obtained by partitioning experiments in the literature according to several factors. The framework has also been extended to the assessment of spatial and temporal characteristics of the attention window, the coordination of multimodal auditory-visual cues in the performance of visual tasks, and the action of multitask load in performance.

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Section: Empirical Results and Taxonomy Of Mechanisms Of Spatialmentioning

confidence: 99%

External Noise Distinguishes Mechanisms of Attention

Lü¹,

Dosher²

2005

Neurobiology of Attention

Self Cite

102

148

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“…The pattern rules out a single-mechanism account of perceptual learning. Two distinct mechanisms of perceptual learning (and attention), one mechanism that is effective only in low-noise displays and another mechanism that is effective only in high-noise displays, have been observed in numerous studies (16,23,24). The fact that one mechanism could be observed without the other mechanism implies that the two mechanisms are independent.…”

Section: Discussionmentioning

confidence: 98%

Perceptual learning in clear displays optimizes perceptual expertise: Learning the limiting process

Dosher

Lü

2005

Proc. Natl. Acad. Sci. U.S.A.

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Human operators develop expertise in perceptual tasks by practice or perceptual learning. For noisy displays, practice improves performance by learned external-noise filtering. For clear displays, practice improves performance by improved amplification or enhancement of the stimulus. Can these two mechanisms of perceptual improvement be trained separately? In an orientation task, we found that training with clear displays generalized to performance in noisy displays, but we did not find the reverse to be true. In noisy displays, the noise in the stimulus limits performance. In clear displays, performance is limited by noisiness of internal representations and processes. Our results suggest that training in one display condition optimizes the limiting factor(s) in performance in that condition and that noise filtering is also improved by exposure to the stimulus in clear displays. The asymmetric pattern of transfer implies the existence of two independent mechanisms of perceptual learning, which may reflect channel reweighting in adult visual system. These results also suggest that training operators with clear stimuli may suffice to improve performance in a range of clear and noisy environments by simultaneous learning by two mechanisms.training procedures ͉ noisy displays ͉ observer models P erceptual learning (1-4) can improve the performance of observers significantly, creating perceptual expertise (5, 6). Practice on a stimulus and task often results in very substantial improvements reflected in improved accuracy or in an ability to perform at a given threshold accuracy level with a more difficult (e.g., lower contrast) stimulus. Also, perceptual learning accrued by practice often exhibits specificities to stimulus characteristics such as retinal position (2, 7), orientation (8, 9), or scale (10, 11), demonstrating perceptual rather than strategic knowledge. Refs. 1 and 12 proposed the possible existence of three independent mechanisms of perceptual learning and empirically documented the existence of two of the mechanisms: external-noise filtering and stimulus amplification. The mechanisms are characterized and tested by a perceptual template model (PTM) of the human observer with titrated external-noise manipulations (12-14). The two mechanisms are important in different environments: external-noise filtering or exclusion in noisy environments and stimulus amplification in clear environments. Perceptual learning in these two mechanisms reflects the improvements in different kinds of limitations: improvements in the quality of the information in the stimulus by external-noise filtering and improvements in the intrinsic limitations in the processing of the human observer by stimulus enhancement.In these investigations of perceptual learning in visual tasks (1, 12, 15), training in high and low noise have always been intermixed, so that the two documented mechanisms have often occurred together as mixtures (for exception, see ref. 16). Single-mechanism models have provided one explanation for simultaneous lea...

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“…First, although attention has been shown to increase contrast appearance for grating stimuli, it is not clear whether the same effect applies to moving random dot stimuli. Indeed, attention was found to have no effect on the contrast sensitivity for a firstorder motion stimulus (Lu, Liu, & Dosher, 2000).l Second, the motion system has a very high contrast sensitivity; that is, responses saturate at very low contrast (Sclar, Maunsell, & Lennie, 1990;Tootell et al, 1995). For example, contrast threshold on motion detection with RDP stimuli is around 5% (rms) for a wide range of coherence levels (Fine, Anderson, Boynton, & Dobkin, 2004).…”

Section: Discussionmentioning

confidence: 99%

Attention alters the appearance of motion coherence

2006

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Selective attention enhances visual information processing, as measured by behavioral performance and neural activity. However, little is known about its effects on subjective experience. Here, we investigated the effect of transient (exogenous) attention on the appearance of visual motion, using a psychophysical procedure that directly measures appearance and controls for response bias. Observers viewed pairs of moving dot patterns and reported the motion direction of the more coherent pattern. Directing attention (via a peripheral precue) to a stimulus location increased its perceived coherence level and improved performance on a direction discrimination task. In a control experiment, we ruled out response bias by lengthening the time interval between the cue and the stimuli, so that the effect of transient attention could no longer be exerted. Our results are consistent with those of neurophysiological studies showing that attention modulates motion processing and provide evidence of a subjective perceptual correlate of attention, with a concomitant effect on performance.

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Attention mechanisms for multi-location first- and second-order motion perception

Cited by 61 publications

References 50 publications

External Noise Distinguishes Mechanisms of Attention

External Noise Distinguishes Mechanisms of Attention

Perceptual learning in clear displays optimizes perceptual expertise: Learning the limiting process

Attention alters the appearance of motion coherence

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