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Intrasaccadic perception triggers pupillary constriction.

Mathôt S, Melmi JB, Castet E - PeerJ (2015)

Bottom Line: As a result, the retinal image was approximately stable for a brief moment during the saccade, and this gave rise to an intrasaccadic percept: A normally invisible stimulus became visible when eye velocity was maximal.Our results confirm and extend previous studies by demonstrating intrasaccadic perception using a reflexive measure (pupillometry) that does not rely on subjective report.Our results further show that intrasaccadic perception affects all stages of visual processing, from the pupillary response to visual awareness.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratoire de Psychologie Cognitive, UMR 7290, Aix-Marseille University/CNRS , Marseille , France.

ABSTRACT
It is commonly believed that vision is impaired during saccadic eye movements. However, here we report that some visual stimuli are clearly visible during saccades, and trigger a constriction of the eye's pupil. Participants viewed sinusoid gratings that changed polarity 150 times per second (every 6.67 ms). At this rate of flicker, the gratings were perceived as homogeneous surfaces while participants fixated. However, the flickering gratings contained ambiguous motion: rightward and leftward motion for vertical gratings; upward and downward motion for horizontal gratings. When participants made a saccade perpendicular to the gratings' orientation (e.g., a leftward saccade for a vertical grating), the eye's peak velocity matched the gratings' motion. As a result, the retinal image was approximately stable for a brief moment during the saccade, and this gave rise to an intrasaccadic percept: A normally invisible stimulus became visible when eye velocity was maximal. Our results confirm and extend previous studies by demonstrating intrasaccadic perception using a reflexive measure (pupillometry) that does not rely on subjective report. Our results further show that intrasaccadic perception affects all stages of visual processing, from the pupillary response to visual awareness.

No MeSH data available.


Related in: MedlinePlus

Orthogonal eye velocity.Eye velocity perpendicular to the saccade direction (orthogonal velocity). (A, B) Vertical eye velocity during horizontal saccades. (C, D) Horizontal velocity during vertical saccades. Individual trials are color coded to indicate peak orthogonal velocity (red: high velocity; blue: low velocity).
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fig-6: Orthogonal eye velocity.Eye velocity perpendicular to the saccade direction (orthogonal velocity). (A, B) Vertical eye velocity during horizontal saccades. (C, D) Horizontal velocity during vertical saccades. Individual trials are color coded to indicate peak orthogonal velocity (red: high velocity; blue: low velocity).

Mentions: Second, vertical saccades are more curved than horizontal saccades (Van der Stigchel & Theeuwes, 2008). Therefore, the velocity component that is perpendicular to the saccade direction (i.e., horizontal velocity during vertical saccades, and vertical velocity during horizontal saccades; from now on: orthogonal velocity) was higher for vertical than horizontal saccades (Fig. 6). This was the case for all participants (two-sided paired-samples t-test using per-participant mean peak orthogonal velocity as dependent measure: t(9) = 10.25, p < .0001). Peak orthogonal velocity during vertical saccades often approached 150°/s. In the No Percept condition, this would have led to partial retinal stabilization of the grating, which is sufficient to trigger an intrasaccadic percept (Garcıa-Pérez & Peli, 2001). In other words, intrasaccadic perception may have triggered a pupillary constriction in both conditions, thus reducing the Condition effect. To control for this, we selected trials on which peak orthogonal velocity was less than the median peak orthogonal velocity (seperately for each participant and saccade direction).


Intrasaccadic perception triggers pupillary constriction.

Mathôt S, Melmi JB, Castet E - PeerJ (2015)

Orthogonal eye velocity.Eye velocity perpendicular to the saccade direction (orthogonal velocity). (A, B) Vertical eye velocity during horizontal saccades. (C, D) Horizontal velocity during vertical saccades. Individual trials are color coded to indicate peak orthogonal velocity (red: high velocity; blue: low velocity).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4558071&req=5

fig-6: Orthogonal eye velocity.Eye velocity perpendicular to the saccade direction (orthogonal velocity). (A, B) Vertical eye velocity during horizontal saccades. (C, D) Horizontal velocity during vertical saccades. Individual trials are color coded to indicate peak orthogonal velocity (red: high velocity; blue: low velocity).
Mentions: Second, vertical saccades are more curved than horizontal saccades (Van der Stigchel & Theeuwes, 2008). Therefore, the velocity component that is perpendicular to the saccade direction (i.e., horizontal velocity during vertical saccades, and vertical velocity during horizontal saccades; from now on: orthogonal velocity) was higher for vertical than horizontal saccades (Fig. 6). This was the case for all participants (two-sided paired-samples t-test using per-participant mean peak orthogonal velocity as dependent measure: t(9) = 10.25, p < .0001). Peak orthogonal velocity during vertical saccades often approached 150°/s. In the No Percept condition, this would have led to partial retinal stabilization of the grating, which is sufficient to trigger an intrasaccadic percept (Garcıa-Pérez & Peli, 2001). In other words, intrasaccadic perception may have triggered a pupillary constriction in both conditions, thus reducing the Condition effect. To control for this, we selected trials on which peak orthogonal velocity was less than the median peak orthogonal velocity (seperately for each participant and saccade direction).

Bottom Line: As a result, the retinal image was approximately stable for a brief moment during the saccade, and this gave rise to an intrasaccadic percept: A normally invisible stimulus became visible when eye velocity was maximal.Our results confirm and extend previous studies by demonstrating intrasaccadic perception using a reflexive measure (pupillometry) that does not rely on subjective report.Our results further show that intrasaccadic perception affects all stages of visual processing, from the pupillary response to visual awareness.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratoire de Psychologie Cognitive, UMR 7290, Aix-Marseille University/CNRS , Marseille , France.

ABSTRACT
It is commonly believed that vision is impaired during saccadic eye movements. However, here we report that some visual stimuli are clearly visible during saccades, and trigger a constriction of the eye's pupil. Participants viewed sinusoid gratings that changed polarity 150 times per second (every 6.67 ms). At this rate of flicker, the gratings were perceived as homogeneous surfaces while participants fixated. However, the flickering gratings contained ambiguous motion: rightward and leftward motion for vertical gratings; upward and downward motion for horizontal gratings. When participants made a saccade perpendicular to the gratings' orientation (e.g., a leftward saccade for a vertical grating), the eye's peak velocity matched the gratings' motion. As a result, the retinal image was approximately stable for a brief moment during the saccade, and this gave rise to an intrasaccadic percept: A normally invisible stimulus became visible when eye velocity was maximal. Our results confirm and extend previous studies by demonstrating intrasaccadic perception using a reflexive measure (pupillometry) that does not rely on subjective report. Our results further show that intrasaccadic perception affects all stages of visual processing, from the pupillary response to visual awareness.

No MeSH data available.


Related in: MedlinePlus