The Fluttering-Heart Illusion: A New Hypothesis

Abstract

The fluttering-heart illusion is a perceived lagging behind of a colour target on a background of a different colour when the two are oscillated together. It has been proposed that the illusion is caused by a differential in the perceptual latencies of different colours (Helmholtz 1867/1962), a differential in rod-cone latencies (von Kries 1896) and rod-cone interactions (von Grünau 1975, 1976 Vision Research 15 431-436, 437-440; 16 397-401; see list of references there). The purpose of this experiment was to assess the hypothesis that the fluttering-heart illusion is caused by a differential in the perceived velocities of chromatic and achromatic motion. To evaluate this hypothesis, we tested observers possessing normal colour vision and deuteranopes. The perceived delay of a chromatic target relative to an achromatic target was measured as a function of background cone contrast and target colour. For observers with normal colour vision, the perceived delay of the chromatic target is greater in the L-S than the L-M testing conditions. The reverse is observed in deuteranope observers. We suggest that this is caused by the absence of an L-M opponent mechanism contributing to chromatic motion in deuteranopes. Greater background cone contrasts tended to yield smaller perceived delays in both normal and deuteranope observers, indicating that greater chromatic modulation decreases the perceived delay of the colour target. These results support the hypothesis that the fluttering-heart illusion can be explained by a differential in the perceived velocities of chromatic and achromatic motion.

Investigating Defensive Colouration in Nudibranch Molluscs using a Novel Analytical Framework for the Study of Animal Colour Patterns​​​​​​​

“…The appearance of our stimuli shares surprisingly strong similarities with several vivid motion and shape illusions (e.g. Nguyen-Tri & Faubert, 2003) which might explain some of the underlying perceptual mechanisms involved. Indeed, unpublished research in R.aculeatus shows that the fish use optic flow for distance estimation (Karlsson, unpublished).…”

Illusory Object Motion in the Centre of a Radial Pattern: The Pursuit-Pursuing Illusion

“…This phenomenon differs from the Fluttering-Heart illusion (Grünau 1975a, 1975b, 1976; Nguyen-Tri and Faubert 2003), where object motion perception is delayed relative to background motion perception, causing apparent phase lags between them resulting in the perception of the stimulus moving back and forth. The presently described phenomenon differs in that it always causes object-motion perception in the direction that is opposite to the surrounding motion, whereas the Fluttering Heart illusion causes this effect for a very short period around the stimulus–motion–direction reversal.…”

“…The presently described phenomenon differs in that it always causes object-motion perception in the direction that is opposite to the surrounding motion, whereas the Fluttering Heart illusion causes this effect for a very short period around the stimulus–motion–direction reversal. This is the case even when the Fluttering Heart illusion is caused by the difference between luminance-defined and colour-defined motions (Nguyen-Tri and Faubert 2003) or by high-contrast and low-contrast motions (Kitaoka and Ashida 2007). In addition, the present illusion (Figure 2b) arises even when viewed in sunlight, whereas the Fluttering-Heart illusion is strongest when viewed under conditions of mesopic vision.…”

“…The Fluttering-Heart illusion (Nguyen-Tri and Faubert 2003; von Grünau 1975a, 1975b, 1976; von Helmholtz 1867/1962; von Kries 1896/1962) causes anomalous motion impression along the object motion path, where object motion perception is delayed relative to background motion perception, causing apparent phase lags between them when they are swinging. This illusion is favored by mesopic vision and a combination of saturated colours (especially a blue object on a red background).…”

The Magnocellular visual pathway and the flash-lag illusion

“…Could we directly perceive the spatial projection predicted by these theories? Work by Nguyen-Tri and Faubert (2003) investigating the fluttering heart illusion (when a colored heart on a differently colored background is moved with that background, it appears to 'drift' on that background) suggests so. They displayed an equiluminant (with background) stimulus and a luminance-modulated stimulus oscillating back and forth on horizontal trajectories one above the other, and asked, "I whether the color target appeared ahead or behind the neutral target in terms of phase (2AFC)."…”