Visuo-haptic interactions with a real object.

<p>Griffiths & Zaidi <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0019877#pone.0019877-Zaidi1" target="_blank">[7]</a> showed that a real flat object with curved edges appears curled in monocular viewing, but the percept can be corrected locally while touching the front edge. To view the illusion, with one eye covered, the shape (A) is held directly in front of the observer, with the straight edges parallel to the line of sight. The shape is then slowly raised until the line of sight is elevated from the horizontal by approximately 45°. The physically flat object then appears to be curled upwards. If the observer holds the object at the tips of the curved edge with both hands, the strength of the illusory percept is reduced, showing that haptic depth information interacts with visual cues. In addition, it is possible to break the illusion by running a finger along the closest edge of the object. If an observer touches one end of the closer curved edge, it is still possible to see the opposite end of the stimulus as having an illusory curl. If the observer then slowly runs a finger along the closer curved edge, the illusion gradually disappears around the region closest to the finger, but returns in the wake of the finger's passage. The effect of the haptic feedback in diminishing the illusory percept is thus local and temporary.</p

Results of Experiment 2.

<p>(A) Symbols: Most frequently reported shape (5 trials×3 observers). Size: Proportion of majority responses per condition. (B) Data panel shows majority shape reported when viewing L-slant and R-slant sinusoidal corrugations covered by random-dot texture with haptic feedback consistent with simulated 3-D shape. Observers viewed the stimulus for 5 sec without haptic-feedback, reported the shape, then touched the stimulus for 40 sec, reported the shape, and then made reports every 5 secs without any additional haptic feedback.</p

Results of Experiment 1.

<p>(A) Symbols: Most frequently reported shape (4 trials×5 observers). Size: Proportion of majority responses per condition. Data panels show majority shape reported at each prompt after a 10 sec interval when viewing sinusoidal corrugations covered by random-dot texture without haptic feedback (B), with haptic feedback consistent with simulated 3-D shape (C), and with haptic feedback opposite to 3-D shape (D). Without haptic feedback, the observers generally perceived concavities and convexities as convex, and both slants as concave; With haptic feedback consistent with the simulated surface, observers gradually started perceiving the concave and slanted surfaces “correctly”. With the haptic feedback opposite to the simulated surface, the observers gradually perceived the surface indicated by the haptic feedback. (E) Shapes reported when viewing sinusoidal corrugations covered by random-dot texture with flat fronto-parallel haptic feedback. This feedback failed to modify the pre-training percept. (F) A flat fronto-parallel surface textured with random dots was tested with convex, concave, right-slant and left-slant haptic feedback. The curved or slanted haptic feedback did not alter the percept of the flat stimulus. (G) When the simulated surfaces were covered by a plaid texture, the observers could perceive the shape correctly, and haptic feedback opposite to the shape did not alter the visual percept.</p

Veridical and non-veridical percepts of 3-D shapes conveyed by surface textures.

<p>(A) Flat fronto-parallel surface and half-cycles of a 3-D vertical sinusoidal corrugation covered with horizontal-vertical plaid textures. (B) Identical surfaces covered with random-dot textures.</p

Results of Experiment 3.

<p>(A) Experiment 3 stimuli: Left-Slant and Right-Slant surfaces covered by random dots, with or without a gap of 0.53 deg in the center. The red squares indicate the location of touching, and the green squares the location of looking. (B) Symbols: Most frequently reported shape (10 trials×3 observers). Size: Proportion of majority responses per condition. (C) Data panel shows shape reported most frequently when viewing L-slant and R-slant sinusoidal corrugations covered by random-dot texture after 40 sec of haptic feedback consistent with simulated 3-D shape. The effect of haptic feedback propagates over the continuous surface although reduced considerably, but is attenuated drastically when a gap interrupts the surface.</p

Frequency distribution of the number of art museum/gallery/exhibition visits reported by the participants.

Frequency distribution of the number of art museum/gallery/exhibition visits reported by the participants.</p

Aesthetic ratings of the image sequences over time.

The different image sequences are represented by distinct colors, which correspond to different sampling intervals. The x-axis indicates the time point at which each image was sampled. The average rating of an image provided is represented by a point.</p

The adjusted R² values and regression coefficients of the principal component regression models.

The adjusted R2 values and regression coefficients of the principal component regression models.</p

The adjusted R² values and regression coefficients of the panel regression models according to the results of the regression subset selection.

The adjusted R2 values and regression coefficients of the panel regression models according to the results of the regression subset selection.</p

Perlin noise flow field.

The gray arrows represent the directions of the force field. The movement of a particle in each frame is affected by the underlying force. The red arrow shows the movement direction of the particle in frame t+1.</p