Ambiguous Figures – What Happens in the Brain When Perception Changes But Not the Stimulus

Abstract

During observation of ambiguous figures our perception reverses spontaneously although the visual information stays unchanged. Research on this phenomenon so far suffered from the difficulty to determine the instant of the endogenous reversals with sufficient temporal precision. A novel experimental paradigm with discontinuous stimulus presentation improved on previous temporal estimates of the reversal event by a factor of three. It revealed that disambiguation of ambiguous visual information takes roughly 50 ms or two loops of recurrent neural activity. Further, the decision about the perceptual outcome has taken place at least 340 ms before the observer is able to indicate the consciously perceived reversal manually. We provide a short review about physiological studies on multistable perception with a focus on electrophysiological data. We further present a new perspective on multistable perception that can easily integrate previous apparently contradicting explanatory approaches. Finally we propose possible extensions toward other research fields where ambiguous figure perception may be useful as an investigative tool.

Evidence for Obliqueness of Angles as a Cue to Planar Surface Slant Found in Extremely Simple Symmetrical Shapes

“…The fact that percepts of positive and negative slant do not co-exist could be the result of a process of mutual inhibition between opponent slant detectors. The suggestion for two groups of competing slant detectors fits in nicely with the results from EEG recordings made during viewing of ambiguous Necker cubes and lattices [48][49][50]. EEG paradigm allowing time-resolved EEG measurement during endogenous perceptual reversals revealed a chain of ERP correlates beginning with an early occipital positivity at around 130 ms (RP, reversal positivity).…”

Dichoptic Viewing Methods for Binocular Rivalry Research: Prospects for Large-Scale Clinical and Genetic Studies

“…Similarly, for an EEG setup with HMD goggles, pre-experimental testing for possible electromagnetic interference and undue pressure and/or movement of the electrodes is also warranted (see Kramberger & Kirbiš, 2011, for a prototype combined HMD/EEG design for studying BR). It is beyond the current paper's scope however to systematically review the dichoptic display methods used across the extensive literature on EEG and evoked potential studies of rivalry (for overview, see Kornmeier & Bach, 2012;Pitts & Britz, 2011;Railo et al, 2011;Regan, 2009;Thomson & Fitzgerald, 2013).…”

How Does the Mind Handle Uncertainty in Ambiguous Figures?

“…Ambiguous figures have attracted the interest of the scientific community because they can be used to investigate potential dissociations between stimulus-driven (sensory) and conceptually-driven (cognitive) processes on a neural basis (Kornmeier & Bach, 2004, 2012Leopold & Logothetis, 1999;Zeki, 2004). When observers fixate on bistable ambiguous figures, perceptual alternations can take place, meaning that either one or the other interpretation is selected by visual awareness (Attneave, 1971;Kornmeier & Bach, 2012;Long & Toppino, 2004, for a review).…”

“…One of the basic assumptions in research on perceptual switching with bistable figures is that the two perceptual states underlying a particular conscious interpretation must be based on the internal neural activity in the brain (Kornmeier & Bach, 2012). This activity can be either endogenously or exogenously induced.…”

“…When observers fixate on bistable ambiguous figures, perceptual alternations can take place, meaning that either one or the other interpretation is selected by visual awareness (Attneave, 1971;Kornmeier & Bach, 2012;Long & Toppino, 2004, for a review). In the four ambiguous figures shown in Figure 1, perceptual bistability implies giving a specific meaning to a particular feature.…”