Object presentations in change blindness

2003

In Encyclopedia of Consciousness, Vol 1. W. Banks (ed). New York: Elsevier. pp. 47-59. , 2009

As observers, we generally have a strong impression of seeing everything in front of us at any moment. But compelling as it is, this impression is false – there are severe limits to what we can consciously experience in everyday life. Much of the evidence for this claim has come from two phenomena: change blindness (CB) and inattentional blindness (IB). CB refers to the failure of an observer to visually experience changes that are easily seen once noticed. This can happen even if the changes are large, constantly repeat, and the observer has been informed that they will occur. A related phenomenon is IB – the failure to visually experience an object or event when attention is directed elsewhere. For example, observers may fail to notice an unexpected object that enters their visual field, even if this object is large, appears for several seconds, and has important consequences for the selection of action. Both phenomena involve a striking failure to report an object or event that is easily seen once noticed. As such, both are highly counterintuitive, not only in the subjective sense that observers have difficulty believing they could fail so badly at seeing but also in the objective sense that these findings challenge many existing ideas about how we see. But as counterintuitive as these phenomena are, progress has been made in understanding them. Indeed, doing so has allowed us to better understand the limitations of human perception in everyday life and to gain new insights into how our visual systems create the picture of the world that we experience each moment our eyes are open.

Communicative & Integrative Biology, 2009

A large body of literature has shown that observers often fail to notice significant changes in visual scenes, even when these changes happen right in front of their eyes. For instance, people often fail to notice if their conversation partner is switched to another person, or if large background objects suddenly disappear. 1,2 These 'change blindness' studies have led to the inference that the amount of information we remember about each item in a visual scene may be quite low. 1 However, in recent work we have demonstrated that long-term memory is capable of storing a massive number of visual objects with significant detail about each item. 3 In the present paper we attempt to reconcile these findings by demonstrating that observers do not experience 'change blindness' with the real world objects used in our previous experiment if they are given sufficient time to encode each item. The results reported here suggest that one of the major causes of change blindness for real-world objects is a lack of encoding time or attention to each object (see also refs. 4 and 5).

This study examined the notion that visually fixating at a stimulus can help prevent change blindness from occurring and looks at change blindness blindness, a common metacognitive error shown by participants. 77 participants were randomly selected and assigned to different conditions. Experimental group had an extra task that they had to perform while attending to the video and the control group only had to watch the video. Participants in both conditions were required to fill out a questionnaire measuring their confidence levels to notice the change. Both conditions failed to detect changes with insignificant difference between the groups, even though the stimulus was visually fixated. Most participants overestimated their change detecting abilities, predicting in the questionnaire that they would notice the change, while in practice they did not. Thus an extra task in the experimental condition did not produce a cognitive overload leading to change blindness. Still participants failed to detect changes when the stimulus was fixated and failed to measure their change detecting abilities realistically.

Vision and Attention, 2001

In the not-too-distant past, vision was often said to involve three levels of processing: a low level concerned with descriptions of the geometric and photometric properties of the image, a high level concerned with abstract knowledge of the physical and semantic properties of the world, and a middle level concerned with anything not handled by the other two. 1 The negative definition of mid-level vision contained in this description reflected a rather large gap in our understanding of visual processing: How could the here-and-now descriptions of the low levels combine with the enduring knowledge of the high levels to produce our perception of the surrounding world?

Visual Cognition, 2012

Wiley Interdisciplinary …, 2011

Change blindness is the failure to notice an obvious change. Inattentional blindness is the failure to notice the existence of an unexpected item. In each case, we fail to notice something that is clearly visible once we know to look for it. Despite similarities, each type of blindness has a unique background and distinct theoretical implications. Here, we discuss the central paradigms used to explore each phenomenon in a historical context. We also outline the central findings from each field and discuss their implications for visual perception and attention. In addition, we examine the impact of task and observer effects on both types of blindness as well as common pitfalls and confusions people make while studying these topics.

The topic of this paper is the complex interaction between attention, fixation, and one species of change blindness. The two main interpretations of the target phenomenon are the 'blindness' interpretation and the 'inaccessibility' interpretation. These correspond to the sparse view (Dennett 1991; Tye, 2007) and the rich view (Dretske 2007; Block, 2007a, 2007b) of visual consciousness respectively. Here I focus on the debate between Fred Dretske and Michael Tye. Section 1 describes the target phenomenon and the dia-lectics it entails. Section 2 explains how attention and fixation weigh in these debates, and argues that Dretske's hyper-rich view fails precisely because he overlooks certain effects of attention and fixation. Section 3 explains why Tye's view is also unsatisfying, mainly because he misconceives the degree of access. Section 4 then puts forward the positive model covariance, which has it that the degree of cognitive access tracks the degree of phenom-enology, and contrasts it with Block's view on the Sperling iconic memory paradigm. The paper ends with a discussion of levels of seeing, which involve crowding, indexing, and other visual phenomena. Change 'blindness' is a set of phenomena that was discovered about two decades ago, yet an entirely satisfying understanding is still lacking. To move forward, a more detailed understanding of attention and fixation is called for.

Encyclopedia of Cognitive Science

South African Journal of Psychology, 2004

This study explored trends in change detection within the change blindness (CB) flicker paradigm. A sample comprising 92 university students was tested for speed in change detection. A number of alternating photographic scenes with and without changes in objects were shown in a computer laboratory. There were significant differences between males and females for central and marginal interest changes on different change types, which included changes in colour, presence and location of objects. The results were used to illustrate the methodological restrictions of previous studies and to expand on theoretical explanations for this phenomenon. This study also challenged the various notions pertaining to the nature of the representations one forms when perceiving visually. The application of connectionist principles revealed the ambiguity of representational-based explanations for change detection.