Figure-ground organization in real and subjective contours: a new ambiguous figure, some novel measures of ambiguity, and apparent distance across regions of figure and ground

Enhancing global thinking can reduce the misconception of accumulation: A potential way to mitigate climate change

Climate change and global warming have long been attention and concern all over the world. However, there is always a debate about when and to what degree to take action like reducing carbon dioxide emissions. Recently, researchers found that the public has misconceptions about climate dynamics, which might be a reason for people do not support prompt mitigation of greenhouse gas emissions. The core problem of misconceptions is the stock-flow (SF) problem, which refers to the difficulty of inferring the behavior of a stock variable given information regarding its inflows and outflows. We elaborated on the idea that global thinking is beneficial for comprehending SF problems and proposed that global thinking enhancing display based on highlighting the areas of difference could be a possible way to shift one's thinking process to the right one, which was proved by two studies. Theoretical and practical implications are discussed.

Illusory edges comingle with real edges in the neural representation of objects

The visual system must transform a point-by-point biological representation from the photoreceptors into neural representations of separate objects. Even a uniform circular patch of light that slowly modulates in luminance can be segmented into separate central and surrounding areas merely by introducing black lines to outline a central square. The black lines cause brightness induction in the center even though the light inside and outside the square is always identical, as predicted by spatial antagonism between the square central area and its surround. Importantly, illusory Kanizsa lines forming the square are as effective for this brightness induction as real black lines, suggesting a 'form-cue invariant' cortical neural representation that does not distinguish between a central region set off by real or illusory edges. An open question is whether separate subsystems generate objects defined by real versus illusory edges, each providing the same form-cue invariant neural representation of an object, or whether form-cue invariance extends to integrating component pieces that together define an object. Experiments here show object segmentation when subparts of a square are defined by a mixture of real and illusory edges. Subjects adjusted the Michelson contrast of a separate patch to match the perceived modulation depth within the central region of a circular field that slowly oscillated in luminance. A closed, four-sided figure, no matter how constructed, reduced the perceived modulation depth within the central region. This shows that both real and illusory subparts can be integrated to segment center from surround. It supports a strong version of form-cue invariance in which neural mechanisms responsible for object segmentation are impartial to the piecemeal cues that are integrated to define an object.

Characterising switching behaviour in perceptual multi-stability

When people experience an unchanging sensory input for a long period of time, their perception tends to switch stochastically and unavoidably between alternative interpretations of the sensation; a phenomenon known as perceptual bi-stability or multi-stability. The huge variability in the experimental data obtained in such paradigms makes it difficult to distinguish typical patterns of behaviour, or to identify differences between switching patterns. Here we propose a new approach to characterising switching behaviour based upon the extraction of transition matrices from the data, which provide a compact representation that is well-understood mathematically. On the basis of this representation we can characterise patterns of perceptual switching, visualise and simulate typical switching patterns, and calculate the likelihood of observing a particular switching pattern. The proposed method can support comparisons between different observers, experimental conditions and even experiments. We demonstrate the insights offered by this approach using examples from our experiments investigating multi-stability in auditory streaming. However, the methodology is generic and thus widely applicable in studies of multi-stability in any domain.

Figure-ground organization in different phases of the perceptual alternation phenomenon

Two experiments on figure-ground organization were designed to examine whether the regions of an ambiguous stimulus perceived as "figure" vary as a function of regional area and experience with the stimulus. In Exp. 1 the perceived duration of each interpretation was recorded during continuous viewing for 10 subjects who had been trained until both percepts appeared with statistical regularity (stationary phase). In Exp. 2 the first interpretation reported by 172 naive observers after a few seconds of pattern exposure was recorded. The well-known tendency to interpret smaller regions as figure was noted in Exp. 2 whereas the results of Exp. 1 suggested equal probability of the percepts. Over-all results suggest that alternation is learned during the transient or "early" phase of perception, with some stimulus features and cultural factors influencing the figure-ground organization. During the stationary or late phase of perception the subject is well practiced and the alternating of interpretations becomes largely automatic.

Occlusion cues contribute to orientation judgments of occlusion-defined contours

Occlusion cues defining a contour in a 2-D stimulus pattern were shown to contribute to the accuracy of orientation judgments of that contour. The stimulus pattern was altered so that the occlusion cues became ambiguous, by introducing a textured background suggesting transparency of the stimulus pattern. Orientation judgments then became significantly less accurate. This finding shows that occlusion cues in 2-D patterns can be behaviorally relevant, in addition to generating the subjective percept commonly known as an illusory contour. The disruptive effect of the textured background on orientation judgments remained when no texture elements were present in the vicinity of the contour. This suggests that the generation of occlusion-defined contours relies as much on an evaluation of the surfaces at either side of the contour as being opaque as it does on local encoding of occlusion cues close to the contour. Finally, orientation sensitivity measured with contours defined by other than occlusion cues was not altered after the introduction of a textured background.

Subjective contours 1900-1990: research trends and bibliography

A bibliography on subjective contours and a brief summary of trends in research on this problem are presented. The bibliography covers the years 1900-1990 and contains 445 entries, each briefly annotated with a code that indicates the general content and theoretical orientation of the item.