Mesopic lightness,brightness, and brightness contrast

At mesopic mean luminances, a fixed luminance contrast produces less brightness contrast than it does at photopic luminances. This suggests that lightnesses of surfaces might also be altered at low luminances. I measured lightness, brightness, and brightness contrast in CRT simulations of achromatic paper patchworks. The illuminance of the standard pattern was fixed, producing 0.12,1.2, or 12 cd/m². The illuminance on the test pattern was varied in a lightness constancy paradigm. Constant brightness contrast required more luminance contrast at lower mean luminances. Failures of lightness constancy occurred at the lowest mean luminances, but they were minor in comparison with the loss of brightness contrast in the same pattern. These results have implications for imaging applications. Often, image content falls in both the photopic and the mesopic ranges. Our results indicate that brightness contrast may decrease substantially in low-luminance regions without large changes of surface lightness.     

T-junctions,apparent depth,and perceived lightness contrast

Observers performed lightness matches for physically equivalent gray targets of a simultaneous lightness contrast display and displays in which both targets were on the same background. Targets either shared a common line-texture pattern with their respective backgrounds or did not. Results indicate that when targets share a line-texture pattern with their respective backgrounds, a contrast effect is obtained. However, when the target's pattern is different than the background's pattern, perceived contrast is significantly reduced and the target appears as a separate 3-D entity. This result applies to both vertically and horizontally oriented displays, to targets that are increments or decrements, and to line-texture patterns that are black or white. Line patterns that are shared by targets and backgrounds result in T-junctions that provide occlusion information. We conclude that targets and backgrounds perceived to be on separate planes because of T-junctions are less likely to be perceptually grouped together and that their luminance values are less likely to be compared with one another.     

The possible loces of lightness contrast

Evidence that the magnitude of simultaneous contrast depends upon retinal orientation of a stimulus configuration is presented in two experiments. More specifically, the magnitude of contrast was found to be greater for stimuli presented horizontally and vertically than for stimuli presented obliquely. These results were interpreted in terms of a cortical analysis of simultaneous contrast.     

A fair test of the effect of a shadow-incompatible luminance gradient on the simultaneous lightness contrast

Shadow-compatibility of simultaneous lightness contrast is discussed by Alexander D Logvinenko and Paola Bressan, with examples claiming to provide a test of the hypothesis.     

Testing discrepancy effects: A critique, a suggestion, and an illustration

To assess the effects of discrepancy between two independent variables, investigators sometimes compute difference scores and correlate such scores with a criterion variable. However, the correlation of the difference with the criterion is accounted for by the correlations of the difference constituents with the criterion and the constituents’ variances. It follows that when investigators are testing a prediction that is not captured by the difference constituents’ main effects, using the difference correlation analysis may be misleading. Under these circumstances, the effects of a discrepancy between two independent variables can be assessed by a test of their interaction. The problems inherent in using difference scores and the advantage of testing the interaction are illustrated in relation to research programs on two separate topics in social psychology.     

Reduction and emergence: a critique of Kim

In a recent critique of the doctrine of emergentism championed by its classic advocates up to C. D. Broad, Jaegwon Kim (Philosophical Studies 63:31–47, 1999) challenges their view about its applicability to the sciences and proposes a new account of how the opposing notion of reduction should be understood. Kim is critical of the classic conception advanced by Nagel and uses his new account in his criticism of emergentism. I question his claims about the successful reduction achieved in the sciences and argue that his new account has not improved on Nagel’s and that the critique of emergentism he bases on it is question-begging in important respects.     

Borderline defenses and Rorschach responses: a critique of Lerner, Albert, and Walsh

Collapsing DSM-III schizotypal and borderline groups to form a borderline population is unwarranted when the results are then related to borderline personality organization. In a comparison of overlapping scoring systems for inferring defensive operations, Lerner, Albert, and Walsh intertwine fact and theory extravagantly and are not justified by their chosen populations nor their assumptions about the theories involved.     

Folkscience: coarse interpretations of a complex reality

The rise of appeals to intuitive theories in many areas of cognitive science must cope with a powerful fact. People understand the workings of the world around them in far less detail than they think. This illusion of knowledge depth has been uncovered in a series of recent studies and is caused by several distinctive properties of explanatory understanding not found in other forms of knowledge. Other experimental work has shown that people do have skeletal frameworks of expectations that constrain richer ad hoc theory construction on the fly. These frameworks are supplemented by an ability to evaluate and rely on the division of cognitive labour in one's culture, an ability shown to be present even in young children.     

Seasonality of suicide in Eastern Europe: a rejoinder to Lester and Moksony

Seasonality of suicide in Hungary decreased from the 1980s to the 1990s, supporting the 2003 conclusion of Lester and Moksony. However, it was the strongest ever to be documented with contemporary suicide data, supporting the conjecture of Voracek, et al. (2002) that seasonality of suicide remains high in Eastern Europe. A new hypothesis regarding the co-occurrence of high incidence and strong seasonality of suicide is presented.     

Concept empiricism: a methodological critique

Thanks to Barsalou's, Damasio's, Glenberg's, Prinz' and others' work, neo-empiricism is gaining a deserved recognition in the psychology and philosophy of concepts. I argue, however, that neo-empiricists have underestimated the difficulty of providing evidence against the amodal approach to concepts and higher cognition. I highlight three key problems: the difficulty of sorting out amodal predictions from neo-empiricist predictions, the difficulty of finding experimental tasks that are not best solved by imagery and the difficulty of generalizing findings concerning a given cognitive process in a given context to other cognitive processes or other contexts. Finally, solutions to these three problems are considered.     

Inhomogeneous surrounds, conflicting frameworks, and the double-anchoring theory of lightness

The empirical question of whether or not the lightness of a region is accounted for purely by the average luminance of its surround has a complex answer that depends on whether such a region is an increment, a decrement, or intermediate relative to the luminances of the contiguous surfaces. It is shown here that a new model of lightness, based on anchoring principles, predicts and clarifies such intricacies. In this model, the luminance of the target region determines its lightness in two ways: indirectly, by causing it to group with parts of its surround and thus defining the nested frameworks to which it belongs; and directly, by anchoring it to the highest luminance and to the average surround luminance in each of these frameworks. Inter- and intraindividual differences in lightness assessment are shown to emerge under grouping conditions that create unstable, conflicting frameworks.     

Photometric, geometric, and perceptual factors in illumination-independent lightness constancy

It has been shown that lightness constancy depends on the articulation of the visual field (Agostini & Galmonte, 1999). However, among researchers there is little agreement about the meaning of "articulation." Beyond the terminological heterogeneity, an important issue remains: What factors are relevant for the stability of surface color perception? Using stimuli with two fields of illumination, we explore this issue in three experiments. In Experiment 1, we manipulated the number of luminances, the number of reflectances, and the number of surfaces and their spatial relationships; in Experiment 2, we manipulated the luminance range; finally, in Experiment 3 we varied the number of surfaces crossed by the illumination edge. We found that there are two relevant factors in optimizing lightness constancy: (1) the lowest luminance in shadow and (2) the co-presence of patches of equal reflectance in both fields of illumination. The latter effect is larger if these patches strongly belong to each other. We interpret these findings within the albedo hypothesis.