Colour in a larger perspective: the rebirth of Gestalt psychology

Gestalt neurons and emergent properties in visual perception: A novel concept for the transformation from local to global processing

Gestalten in visual perception are defined by emergent properties of the whole, which cannot be predicted from the sum of its parts; rather, they arise by virtue of inherent principles, the Laws of Seeing. This review attempts to assign neurophysiological correlates to select emergent properties in motion and contour perception and proposes parallels to the processing of local versus global attributes by classical versus contextual receptive fields. The aim is to identify Gestalt neurons in the visual system to account for the Laws of Seeing in causal terms and to explain "Why do things look as they do" (Koffka, 1935, p. 76).

Contradictory influence of context on predominance during binocular rivalry

BACKGROUND

Binocular rivalry is a complex process characterised by alternations in perceptual suppression and dominance that result when two different images are presented simultaneously to the left and right eyes. It has been reported recently that the addition of contextual cues will promote the predominance of the context consistent rivalry target. In contrast to Levelt's second proposition (1965), this effect has been found to result exclusively from an increase in the dominance phase duration, while the suppression phase duration remains unaffected.

METHODS

Human subjects were simultaneously presented with a small (2 degrees ) disc consisting of gratings (four cycles per degree) of different orientations to the two eyes. Four experiments were conducted to ascertain the effects of background gratings and contextual colour information on target predominance and phase duration. For each of the four experimental conditions, the orientation and colour of the target gratings and surrounding contextual background were systematically manipulated.

RESULTS

In this study, we report an effect opposite to that of Levelt. Contradictory contextual information increases target predominance and phase duration during binocular rivalry. Our results demonstrate that it is possible to promote the dominance of the context contradictory percept with co-linearity, co-chromaticity and orientation cues. In line with previous studies involving context, we find that this effect on predominance is due to an increase in the duration of the dominance rather than the suppression phase.

DISCUSSION

We discuss our findings in respect to those from previous studies and consider high- and low-level processes that may be responsible for these apparently 'contradictory' roles of context on binocular rivalry. In addition, we discuss how the apparent 'anti-Levelt' effect of context can be reinterpreted in a manner that brings it back in line with Levelt's second proposition and raises the question of whether 'suppressability' plays a disproportionately large role in determining the duration of perceptual phases in binocular rivalry.

Measuring the Breathing Light Illusion by means of induced simultaneous contrast

By blurring the margins of a surface, both its brightness and the perceived contrast against a superimposed figure with sharp boundaries increase. Also, if one approaches a blurred white spot on a grey background, this spot will appear wider and brighter: this phenomenon is known as the Breathing Light Illusion (BLI) (Gori and Stubbs, 2006 Perception 35 1573-1577). We studied the increment of the achromatic contrast of a grey sharp-boundary disk when it was superimposed on the BLI. This augmentation of the perceived contrast in the dynamic presentation of the BLI was significantly stronger than the effect that Agostini and Galmonte (2002a Psychonomic Bulletin and Review 9 264-269) obtained in static presentation. Our study leads to an indirect quantification of the BLI. Two control experiments showed that the increment of the achromatic contrast depends on the blurred spot and is independent of the dynamic increment in angular size. These results argue for a causal relationship between the increase in brightness due to the BLI and the darkening of the superimposed disk.

A psicologia da gestalt e a ciência empírica contemporânea

Wertheimer realizou um experimento que era explicado seguindo-se fatores holísticos gestálticos, e isto há mais de noventa anos. Apesar disso, estudos recentes demonstram a vivacidade desse tipo de explicação. Basicamente, ao se observar coisas do mundo, observa-se suas formas ou melhor suas Gestalten. A seguir, pode-se dividir essas Gestalten em partes. Porém cada parte será sempre parte daquela Gestalt que lhe deu inicio e não um elemento constituinte básico. A teoria da Gestalt não é exclusivamente psicológica, como o demonstraram principalmente Wertheimer, Köhler e Koffka. Iniciou-se com um experimento sobre a visão de movimentos correspondendo a estímulos estáticos, mas continuou propondo-se inclusive, de um lado, uma Gestalt física formada da corrente elétrica gestálticas dentro de um condutor ou, de outro, uma Gestalt sociológica formada de muitos seres humanos, como o dançar de pares ao som de um samba realizado por um grupo de músicos.

Sentences and rehearsals increase rated similarity: support for assimilation-in-salience theory

The present study concerns how organization produces good retention. Exp. 1 indicated that college students rated two words in sentences as more similar than the same two words alone. In Exp. 2 they rated the two words of old presumably rehearsed pairs as more similar than the two words of new pairs. A sentence is a type of organization, and words that are rehearsed together are frequently subjectively organized. Therefore, the two experiments suggest that organized stimuli also assimilate among themselves (and evidence in the literature concurs). Organized stimuli also produce a highly salient (activated) single memorial group (unit) such as the meaning that a simple sentence comes to have according to evidence in the literature. So, the two experiments support the hypothesis that organized stimuli produce good retention, assimilation among themselves, and a highly salient group. Consequently, organized stimuli may also assimilate to the highly salient group and thereby increase in salience, with this increase enabling the good retention. This assimilation-in-salience theory of how organization produces good retention accords with perceptual evidence suggesting that a target increases in salience through its assimilation to a more salient simultaneously present context.