Large changes in a scene often become difficult to notice if made during an eye movement, image flicker, movie cut, or other such disturbance. It is argued here that this _change blindness_ can serve as a useful tool to explore various aspects of vision. This argument centers around the proposal that focused attention is needed for the explicit perception of change. Given this, the study of change perception can provide a useful way to determine the nature of visual attention, and (...) to cast new light on the way that it is?and is not?involved in visual perception. To illustrate the power of this approach, this paper surveys its use in exploring three different aspects of vision. The first concerns the general nature of _seeing_. To explain why change blindness can be easily induced in experiments but apparently not in everyday life, it is proposed that perception involves a _virtual representation_, where object representations do not accumulate, but are formed as needed. An architecture containing both attentional and nonattentional streams is proposed as a way to implement this scheme. The second aspect concerns the ability of observers to detect change even when they have no visual experience of it. This _sensing_ is found to take on at least two forms: detection without visual experience (but still with conscious awareness), and detection without any awareness at all. It is proposed that these are both due to the operation of a nonattentional visual stream. The final aspect considered is the nature of visual attention itself?the mechanisms involved when _scrutinizing_ items. Experiments using controlled stimuli show the existence of various limits on visual search for change. It is shown that these limits provide a powerful means to map out the attentional mechanisms involved. (shrink)

Non-sensory experiences represent almost all context information in consciousness. They condition most aspects of conscious cognition including voluntary retrieval, perception, monitoring, problem solving, emotion, evaluation, meaning recognition. Many peculiar aspects of non-sensory qualia (e.g., they resist being 'grasped' by an act of attention) are explained as adaptations shaped by the cognitive functions they serve. The most important nonsensory experience is coherence or "rightness." Rightness represents degrees of context fit among contents in consciousness, and between conscious and non-conscious processes. Rightness (not (...) familiarity) is the feeling-of-knowing in implicit cognition. The experience of rightness suggests that neural mechanisms "compute" signals indicating the global dynamics of network integration. (shrink)

Evidence from many different paradigms (e.g. change blindness, inattentional blindness, transsaccadic integration) indicate that observers are often very poor at reporting changes to their visual environment. Such evidence has been used to suggest that the spatio-temporal coherence needed to represent change can only occur in the presence of focused attention. In four experiments we use modified change blindness tasks to demonstrate (a) that sensitivity to change does occur in the absence of awareness, and (b) this sensitivity does not rely on (...) the redeploy- ment of attention. We discuss these results in relation to theories of scene percep- tion, and propose a reinterpretatio n of the role of attention in representing change. (shrink)

This paper reviews the history of psychological investigations of unconscious perception and summarizes the current status of experimental research in this area of investigation. The research findings described in the paper illustrate how it is possible to distinguish experimentally between conscious and unconscious perception. The most successful experimental strategy has been to show that a stimulus can have qualitatively different consequences on cognitive and affective reactions depending on whether it was consciously or unconsciously perceived. In addition, recent studies of patients (...) undergoing general anaesthesia have shown that the effects of stimuli perceived unconsciously during surgery can last for approximately 24 hours. Taken together, the results of these recent psychological investigations provide empirical support for the importance of unconsciously perceived information in determining cognitive and affective reactions. (shrink)