A Psychophysiological Investigation of the Rorschach Colour and Form Determinants

The Rorschach colour-emotion and form-control hypotheses were investigated by determining whether subjects would react differently psychophysiologically while giving colour dominant or form responses. Slides of the Rorschach plates no. II, III, V, VIII, IX and X were presented to 42 subjects while respiration (as control only) vasomotor changes, skin resistance and heart rate were recorded. All physiological changes (except respiration) found in conjunction with Rorschach C, CF, FC, and F responses were transformed to Lacey's autonomic lability scores. Some indications of different physiological reactions to colour and form were found. The results indicated the possible existence of “emotional” and “controlled” groups of subjects who tended to react differently, verbally and physiologically, to the Rorschach stimuli.     

Fine-Grained Colour Discrimination without Fine-Grained Colour

René Jagnow [2012] argues that David Rosenthal's theory of consciousness cannot account for certain experiences that involve colours so fine-grained that we do not and cannot have concepts of them. Jagnow claims that an appeal to comparative concepts such as being slightly darker than cannot help Rosenthal, since, in order to apply such concepts, we would already need to be conscious of two distinct fine-grained colours. The present paper contests this claim. It appeals to the Cornsweet illusion and some other visual phenomena, in order to argue that our visual systems can and do represent brutely comparative matters.     

Colour for Representationalists

Redness is the property that makes things look red in normal circumstances. That seems obvious enough. But then colour is whatever property does that job: a certain reflectance profile as it might be. Redness is the property something is represented to have when it looks red. That seems obvious enough. But looking red does not represent that which looks red as having a certain reflectance profile. What should we say about this antinomy and how does our answer impact on the contest between realism and subjectivism about colour? I address the issues through the lens of a representationalist position on colour experience.     

Colour constancy and Fregean representationalism

All representationalists maintain that there is a necessary connection between an experience’s phenomenal character and intentional content; but there is a disagreement amongst representationalists regarding the nature of those intentional contents that are necessarily connected to phenomenal character. Russellian representationalists maintain that the relevant contents are composed of objects and/or properties, while Fregean representationalists maintain that the relevant contents are composed of modes of presentation of objects and properties. According to Fregean representationalists such as David Chalmers and Brad Thompson, the Fregean variety of the view is preferable to the Russellian variety because the former can accommodate purported counterexamples involving spectrum inversion without illusion and colour constancy while the latter cannot. I maintain that colour constancy poses a special problem for the Fregean theory in that the features of the theory that enable it handle spectrum inversion without illusion cannot be extended to handle colour constancy. I consider the two most plausible proposals regarding how the Fregean view might be developed in order to handle colour constancy—one of which has recently been defended by Thompson (Australas J Philos 87:99–117, 2009)—and argue that neither is adequate. I conclude that Fregean representationalism is no more able to accommodate colour constancy than is Russellian representationalism and, as such, ought to be rejected.     

Colour Inversion Problems for Representationalism

In this paper I examine whether representationalism can account for various thought experiments about colour inversions. Representationalism is, at minimum, the view that, necessarily, if two experiences have the same representational content then they have the same phenomenal character. I argue that representationalism ought to be rejected if one holds externalist views about experiential content and one holds traditional externalist views about the nature of the content of prepositional attitudes. Thus, colour inversion scenarios are more damaging to externalist representationalist views than have been previously thought. More specifically, I argue that representationalists who endorse externalism about experiential content either have to become internalists about the content of prepositional attitudes or they have to adopt a novel variety of externalism about the content of prepositional attitudes. This novel type of prepositional attitude externalism is investigated. It can be seen that adopting it forces one to reject Putnam's and Burge's externalist considerations about the nature of the prepositional attitudes.     

Constraints on Colour Category Formation

This article addresses two questions related to colour categorization, to wit, the question what a colour category is, and the question how we identify colour categories. We reject both the relativist and universalist answers to these questions. Instead, we suggest that colour categories can be identified with the help of the criterion of psychological saliency, which can be operationalized by means of consistency and consensus measures. We further argue that colour categories can be defined as well-structured entities that optimally partition colour space. We provide some empirical support for this claim by presenting experimental results, which indicate that internal structure is a better predictor of colour categories than perceptual saliency.     

Colour and spatial cueing in low-prevalence visual search

People are able to judge the current position of occluded moving objects. This operation is known as motion extrapolation. It has previously been suggested that motion extrapolation is independent of the oculomotor system. Here we revisited this question by measuring eye position while participants completed two types of motion extrapolation task. In one task, a moving visual target travelled rightwards, disappeared, then reappeared further along its trajectory. Participants discriminated correct reappearance times from incorrect (too early or too late) with a two-alternative forced-choice button press. In the second task, the target travelled rightwards behind a visible, rectangular occluder, and participants pressed a button at the time when they judged it should reappear. In both tasks, performance was significantly different under fixation as compared to free eye movement conditions. When eye movements were permitted, eye movements during occlusion were related to participants' judgements. Finally, even when participants were required to fixate, small changes in eye position around fixation (<2°) were influenced by occluded target motion. These results all indicate that overlapping systems control eye movements and judgements on motion extrapolation tasks. This has implications for understanding the mechanism underlying motion extrapolation.     

Colour and spatial cueing in low-prevalence visual search

In visual search, 30-40% of targets with a prevalence rate of 2% are missed, compared to 7% of targets with a prevalence rate of 50% (Wolfe, Horowitz, & Kenner, 2005). This "low-prevalence" (LP) effect is thought to occur as participants are making motor errors, changing their response criteria, and/or quitting their search too soon. We investigate whether colour and spatial cues, known to improve visual search when the target has a high prevalence (HP), benefit search when the target is rare. Experiments 1 and 2 showed that although knowledge of the target's colour reduces miss errors overall, it does not eliminate the LP effect as more targets were missed at LP than at HP. Furthermore, detection of a rare target is significantly impaired if it appears in an unexpected colour-more so than if the prevalence of the target is high (Experiment 2). Experiment 3 showed that, if a rare target is exogenously cued, target detection is improved but still impaired relative to high-prevalence conditions. Furthermore, if the cue is absent or invalid, the percentage of missed targets increases. Participants were given the option to correct motor errors in all three experiments, which reduced but did not eliminate the LP effect. The results suggest that although valid colour and spatial cues improve target detection, participants still miss more targets at LP than at HP. Furthermore, invalid cues at LP are very costly in terms of miss errors. We discuss our findings in relation to current theories and applications of LP search.     

Colour inputs to random-dot stereopsis.

Recently it has been claimed by Livingstone and Hubel that, of three anatomically and functionally distinct visual channels (the magnocellular, parvocellular interblob, and blob channels), only the magnocellular channel is involved in the processing of stereoscopic depth. Since the magnocellular system shows little overt colour opponency, the reported loss of the ability to resolve random-dot stereograms defined only by colour contrast seems consistent with this view. However, Julesz observed that reversed-contrast stereograms could be fused if correlated colour information was added. In the present study, 'noise' (non-corresponding) pixels were injected into random-dot stereograms in order to increase fusion time. All six subjects tested were able to achieve stereopsis in less than three minutes when there was only correspondence in colour and not in luminance, and three when luminance contrast was completely reversed. This ability depends on information about the direction of colour contrast, not just the presence of chromatic borders. When luminance and chromatic contrast are defined in terms of signal-to-noise ratios at the photoreceptor mosaic, chromatic information plays at least as important a role in stereopsis as does luminance information, suggesting that the magnocellular channel is not uniquely involved.     

Colour blindness adversely impacts face recognition

ABSTRACT

Whether colour information contributes to the process of face recognition remains controversial. We examine this question here by evaluating the face recognition performance of individuals who are colour blind. Specifically, we compared the performance profile of colour blind and matched control individuals on a colour face recognition task where shape information was progressively degraded. The colour blind participants performed significantly more poorly than controls on this task, as revealed through multiple dependent measures. There was, however, no difference between these two groups on a standardized grayscale control task of face recognition, ruling out a generic face recognition deficit. These results both uncover a face recognition deficit in colour blind individuals and provide evidence for the contribution of colour to everyday facial recognition.     

Colour associates to semantic linear orders

Summary People were asked whether they had strong colour associates (rather than associations) for different linear orders. Eighteen informants responded that they associated colours with numbers, and ten that they associated colours with the days of the week. The colours associated with both linear orders were consistent between subjects and correlated with each other. The order of the associates correlated with the order noted in the anthropological linguistic typology of Berlin and Kay (1969). Together, the patterns noted indicate that the association of colours with linear orders is an orderly cognitive phenomenon. While no causal explanation of the phenomenon is given, some implications are suggested.     

Colour vision brings clarity to shadows

We have revealed a new role for colour vision in visual scene analysis: colour vision facilitates shadow identification. Shadows are important features of the visual scene, providing information about the shape, depth, and movement of objects. To be useful for perception, however, shadows must be distinguished from other types of luminance variation, principally the variation in object reflectance. A potential cue for distinguishing shadows from reflectance variations is colour, since chromatic changes typically occur at object but not shadow boundaries. We tested whether colour cues were exploited by the visual system for shadow identification, by comparing the ability of human test subjects to identify simulated shadows on chromatically variegated versus achromatically variegated backgrounds with identical luminance compositions. Performance was superior with the chromatically variegated backgrounds. Furthermore, introducing random colour contrast across the shadow boundaries degraded their identification. These findings demonstrate that the visual system exploits inbuilt assumptions about the relationships between colour and luminance in the natural visual world.