Learning to ignore the mask in texture segmentation tasks.

Schubö, Anna; Schlaghecken, Friederike; Meinecke, Cristina

doi:10.1037/0096-1523.27.4.919

Cited by 29 publications

(28 citation statements)

References 46 publications

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“…Given that subjects could not infer the precise moment of appearance of the target (randomized fixation period, randomized SOAs), learning effects cannot be attributed to an improved focusing of attention in time. Another possibility is that subjects learned to suppress the mask, as has been found for pattern masking (14,15). This hypothesis cannot be directly tested in metacontrast masking because the mask cannot be changed for a given target.…”

Section: Discussionmentioning

confidence: 83%

Subjective and objective learning effects dissociate in space and in time

Schwiedrzik

Singer

Melloni

2011

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

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Perceptual learning not only improves sensitivity, but it also changes our subjective experience. However, the question of how these two learning effects relate is largely unexplored. Here we investigate how subjects learn to see initially indiscriminable metacontrast-masked shapes. We find that sensitivity and subjective awareness increase with training. However, sensitivity and subjective awareness dissociate in space: Learning effects on performance are lost when the task is performed at an untrained location in another quadrant, whereas learning effects on subjective awareness are maintained. This finding indicates that improvements in shape sensitivity involve visual areas up to V4, whereas changes in subjective awareness involve other brain regions. Furthermore, subjective awareness dissociates from sensitivity in time: In an early phase of perceptual learning, subjects perform above chance on trials that they rate as subjectively invisible. Later, this phenomenon disappears. Subjective awareness is thus neither necessary nor sufficient for achieving above-chance objective performance.consciousness | psychophysics | Signal Detection Theory O ur perceptual apparatus is constantly shaped by experience. This fact has been shown, for example, in experiments investigating perceptual learning, where practice on a sensory task leads to increases in perceptual sensitivity (1). Although perceptual learning is a well-studied phenomenon, the question of how it changes subjective awareness has rarely been addressed. Do we actually "see more" after training? Apart from anecdotal reports pointing in this direction, a quantitative analysis of the effects of learning on subjective awareness is largely missing (2) because studies in perceptual learning have almost exclusively focused on objective task performance [i.e., sensitivity in terms of signal detection theory (3)]. However, studies from a different line of research, namely those investigating conscious perception, have found that objective performance in a task and awareness of the stimuli on which the task is performed can dissociate. Such is the case in blindsight (4) but also is found in normal observers (refs. 5-7 but see ref. 8). These data demonstrate that these two aspects of perception cannot be treated as being equivalent. We have recently shown that subjects can be trained to perform on and to see stimuli that are initially invisible to them (9). We thus hypothesize that awareness is trainable, a conclusion that is in accordance with recent findings in blindsight patients (10). However, the time course of those learning effects has not been explored, i.e., whether the improvements in sensitivity and subjective awareness depend on each other. In particular, changes in sensitivity could be a prerequisite for changes in subjective awareness. Alternatively, it could be necessary to subjectively see a stimulus in order for changes in sensitivity to occur. Last but not least, training could affect sensitivity and subjective awareness in parallel without any mut...

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Section: Discussionmentioning

confidence: 83%

Subjective and objective learning effects dissociate in space and in time

Schwiedrzik

Singer

Melloni

2011

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

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“…Typical examples are target textures embedded in a surrounding texture followed by a backward masking texture, for example, in perceptual learning (e.g. Karni & Sagi, 1993;Schubö et al, 2001) and in texture discrimination (e.g. Caputo, 1998;Meinhardt, Schmidt, Persike, & Röers, 2004).…”

Section: Discussionmentioning

confidence: 99%

Combining simultaneous with temporal masking.

Hermens¹,

Herzog²,

Francis³

2009

Journal of Experimental Psychology: Human Perception and Perfor

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Simultaneous and temporal masking are two frequently used techniques in psychology and vision science. While there are many studies and theories related to each masking technique, there are no systematic investigations of their mutual relationship, even though both techniques are often applied together. Here, we show that temporal masking can both undo and enhance the deteriorating effects of simultaneous masking depending on the stimulus onset asynchrony between the simultaneous and temporal mask. For the task and stimuli used in this study, temporal masking was largely unaffected by the properties of the simultaneous mask. In contrast, simultaneous masking seems to depend strongly on spatial grouping and was strongly affected by the properties of the temporal mask. These findings help to identify the nature of both temporal and simultaneous masking and promote understanding of the role of spatial and temporal grouping in visual perception.

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“…Each trial began with a 33-ms prime immediately followed by a 100-ms mask, both presented at fixation. A new random mask was constructed on each trial in order to avoid perceptual learning of the mask and correspondingly increased prime identification (Schubö et al 2001;Schlaghecken et al 2008). In a staircase procedure, prime identification performance under these particular stimulus and timing conditions was at chance level (Schlaghecken et al submitted).…”

Section: Methodsmentioning

confidence: 99%

Either or neither, but not both: locating the effects of masked primes

2008

Self Cite

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Execution of a response that has been primed by a backward-masked stimulus is inhibited (negative compatibility effect; NCE). Three experiments investigated the locus of this inhibition. Masked primes (left-or right-pointing arrows) were followed either by an arrow or a circle target. Arrow targets always required a left-or right-hand response, but the experiments differed in the response required to circles: press neither, either or both response keys (i.e. nogo, free choice and bimanual, respectively). Arrow targets showed the usual NCEs. Circle targets showed NCEs in the form of a response bias away from the primed response in the nogo and free-choice tasks; primes and targets differed on these trials, ruling out a perceptual explanation of the NCE. The bimanual task showed no such bias, suggesting that the NCE is located at a level of abstract response codes rather than specific muscle commands.

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Learning to ignore the mask in texture segmentation tasks.

Cited by 29 publications

References 46 publications

Subjective and objective learning effects dissociate in space and in time

Subjective and objective learning effects dissociate in space and in time

Combining simultaneous with temporal masking.

Either or neither, but not both: locating the effects of masked primes

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