Color Constancy for an Unseen Surface

A theory of visibility measures in the dissociation paradigm

Research on perception without awareness primarily relies on the dissociation paradigm, which compares a measure of awareness of a critical stimulus (direct measure) with a measure indicating that the stimulus has been processed at all (indirect measure). We argue that dissociations between direct and indirect measures can only be demonstrated with respect to the critical stimulus feature that generates the indirect effect, and the observer's awareness of that feature, the critical cue. We expand Kahneman's (Psychological Bulletin, 70, 404-425, 1968) concept of criterion content to comprise the set of all cues that an observer actually uses to perform the direct task. Different direct measures can then be compared by studying the overlap of their criterion contents and their containment of the critical cue. Because objective and subjective measures may integrate different sets of cues, one measure generally cannot replace the other without sacrificing important information. Using a simple mathematical formalization, we redefine and clarify the concepts of validity, exclusiveness, and exhaustiveness in the dissociation paradigm, show how dissociations among different awareness measures falsify both single-valued measures and monocausal theories of "consciousness," and formulate the demand that theories of visual awareness should be sufficiently specific to explain dissociations among different facets of awareness.

Implicit bias training can remove bias from subliminal stimuli, restoring choice divergence: A proof-of-concept study

Subliminal information can influence our conscious life. Subliminal stimuli can influence cognitive tasks, while endogenous subliminal neural information can sway decisions before volition. Are decisions inextricably biased towards subliminal information? Or can they diverge away from subliminal biases via training? We report that implicit bias training can remove biases from subliminal sensory primes. We first show that subliminal stimuli biased an imagery-content decision task. Participants (n = 17) had to choose one of two different patterns to subsequently imagine. Subliminal primes significantly biased decisions towards imagining the primed option. Then, we trained participants (n = 7) to choose the non-primed option, via post choice feedback. This training was successful despite participants being unaware of the purpose or structure of the reward schedule. This implicit bias training persisted up to one week later. Our proof-of-concept study indicates that decisions might not always have to be biased towards non-conscious information, but instead can diverge from subliminal primes through training.

Visual-auditory interactions on explicit and implicit information processing

Interactions among sensory information are important for generating a coherent percept of the external world. Facilitation and inhibition effects in cross-modal perception have been widely studied for decades. The present study tried to confirm the interaction effects between sensory information in a bimodal context and explore these influences when part of the sensory information was presented without participants' subjective awareness. A total of 40 undergraduate participants were recruited in this mixed design study. Participants were required to count the flashing of the black circle (visual task) or the presentation frequency of the beep sound (auditory task) with the presence of either congruent or incongruent sensory signals in the background. Participants in the explicit group generally performed more accurately and also faster with the congruent stimuli than with the incongruent stimuli. Performance accuracy in the visual task in the implicit group was affected by the non-target sound signals which were presented beneath participants' subjective awareness. The better performance yielded in the auditory task than in the visual task was explained by the appropriateness of the auditory stimulation to the task nature. In addition, the supportive findings regarding processing without awareness should be interpreted with caution.

The nature of shape constancy mechanisms as revealed by shape priming

Five shape priming experiments are reported in which the target was either a five- or six-sided line-drawn figure and participants made a speeded two-alternative forced-choice judgment about the target's number of sides. On priming trials, the target was preceded by a briefly presented smaller line figure (the prime) and performance on these trials was gauged relative to a no-prime condition. In the first two experiments, primes were rendered invisible by the presentation of a backwards visual noise mask, respectively for a short (∼40 ms) or long duration (∼93 ms). No reliable priming effects arose under masked conditions. When these experiments were repeated without the mask, participants were speeded when the prime and target were related by a rigid through-the-plane rotation but not when the prime was a nonrigid, stretched version of the target. The same pattern of priming effects arose when, in a final experiment, novel irregular shapes were used. Collectively, the data reveal the operation of shape constancy mechanisms that are particularly sensitive to shape rigidity. The findings suggest that the visual system attempts to secure a correspondence between the rapid and successive presentations of the prime and the target by matching shapes according to a rigidity constraint.

Unitary and dual models of phenomenal consciousness

There is almost unanimous consensus among the theorists of consciousness that the phenomenal character of a mental state cannot exist without consciousness. We argue for a reappraisal of this consensus. We distinguish two models of phenomenal consciousness: unitary and dual. Unitary model takes the production of a phenomenal quality and it's becoming conscious to be one and the same thing. The dual model, which we advocate in this paper, distinguishes the process in which the phenomenal quality is formed from the process that makes this quality conscious. We put forward a conceptual, methodological, neuropsychological and neural argument for the dual model. These arguments are independent but provide mutual support to each other. Together, they strongly support the dual model of phenomenal consciousness and the concomitant idea of unconscious mental qualities. The dual view is thus, we submit, a hypothesis worthy of further probing and development.

Perception and Cognition Are Largely Independent, but Still Affect Each Other in Systematic Ways: Arguments from Evolution and the Consciousness-Attention Dissociation

The main thesis of this paper is that two prevailing theories about cognitive penetration are too extreme, namely, the view that cognitive penetration is pervasive and the view that there is a sharp and fundamental distinction between cognition and perception, which precludes any type of cognitive penetration. These opposite views have clear merits and empirical support. To eliminate this puzzling situation, we present an alternative theoretical approach that incorporates the merits of these views into a broader and more nuanced explanatory framework. A key argument we present in favor of this framework concerns the evolution of intentionality and perceptual capacities. An implication of this argument is that cases of cognitive penetration must have evolved more recently and that this is compatible with the cognitive impenetrability of early perceptual stages of processing information. A theoretical approach that explains why this should be the case is the consciousness and attention dissociation framework. The paper discusses why concepts, particularly issues concerning concept acquisition, play an important role in the interaction between perception and cognition.

The contribution of single case studies to the neuroscience of vision

Visual neuroscience is concerned with the neurobiological foundations of visual perception, that is, the morphological, physiological, and functional organization of the visual brain and its co-operative partners. One important approach for understanding the functional organization of the visual brain is the study of visual perception from the pathological perspective. The study of patients with focal injury to the visual brain allows conclusions about the representation of visual perceptual functions in the framework of association and dissociation of functions. Selective disorders have been reported for more "elementary" visual capabilities, for example, color and movement vision, but also for visuo-cognitive capacities, such as visual agnosia or the visual field of attention. Because these visual disorders occur rather seldom as selective and specific dysfunctions, single cases have always played, and still play, a significant role in gaining insights into the functional organization of the visual brain.