Dartnall claims that visual short-term memory stores nonconceptual content , in the form of compressed images. In this paper I argue against the claim that NCC can be stored in VSTM. I offer four reasons why NCC cannot be stored in visual memory and why only conceptual information can: NCC lasts for a very short time and does not reach either visual short-term memory or visual long-term memory; the content of visual states is stored in memory only if and when (...) object-centered attention modulates visual processing and this modulation signifies the onset of the conceptualization of that content; only categorical high-level information that characterizes conceptual content and not metric and precise iconic information that characterizes NCC can be stored in visual memory for long periods; and if NCC were stored in visual memory then this would allow recognitional judgments pertaining to NCC—one could recognize the precise shade of a color that one had seen before. However NCC does not allow such recognitional judgments. (shrink)

In this chapter I argue that despite its current popularity the doctrine of the specious present, or at least every current version of it, should be rejected. I describe two alternative accounts, which deal with experiences of two different kinds of change. The first is what I call the dynamic snapshot theory, which accounts for the way we experience continuous changes such as motion and other motion-like phenomena. The second account deals with the way we experience discontinuous changes, those for (...) which there is no finite rate of change. However I then argue that much of the current debate implicitly presupposes a problematic Cartesian view about the nature of conscious experience. If this view is rejected – as I think it should be – then a different kind of account emerges that avoids commitment both to the specious present and to its main current rival, the cinematic view. (shrink)

We investigated whether a pre-change representation is inhibited or weakened under correct change detection. Two arrays of six objects were rapidly presented for change detection in three experiments. After detection, the perceptual identification of degraded stimuli was tested in Experiments 1 and 2. The weakening of a pre-change representation was not observed under correct detection. The repetition priming effect was observed for a pre-change object and the magnitude was equivalent to the effect for a post-change object. Under change blindness, repetition (...) priming for a pre-change representation was observed when detection did not require report of location in Experiment 1 and was not observed when location was required to be reported in Experiment 2. The results of Experiment 3 showed that a pre-change representation was recognized at a higher rate under correct detection than under change blindness, reflecting a stronger rather than a weaker pre-change representation in the former context. (shrink)

Colour has been shown to facilitate the recognition of scene images, but only when these images contain natural scenes, for which colour is ‘diagnostic’. Here we investigate whether colour can also facilitate memory for scene images, and whether this would hold for natural scenes in particular. In the first experiment participants first studied a set of colour and greyscale natural and man-made scene images. Next, the same images were presented, randomly mixed with a different set. Participants were asked to indicate (...) whether they had seen the images during the study phase. Surprisingly, performance was better for greyscale than for coloured images, and this difference is due to the higher false alarm rate for both natural and man-made coloured scenes. We hypothesized that this increase in false alarm rate was due to a shift from scrutinizing details of the image to recognition of the gist of the image. A second experiment, utilizing images without a nameable gist, confirmed this hypothesis as participants now performed equally on greyscale and coloured images. In the final experiment we specifically targeted the more detail-based perception and recognition for greyscale images versus the more gist-based perception and recognition for coloured images with a change detection paradigm. The results show that changes to images are detected faster when image-pairs were presented in greyscale than in colour. This counterintuitive result held for both natural and man-made scenes and thus corroborates the shift from more detailed processing of images in greyscale to more gist-based processing of coloured images. (shrink)

Studies of change detection suggest that people tend to overestimate their ability to detect visual changes. In a recent laboratory study of change detection and human intention, Beck et al., found that individuals have an inadequate understanding that intention can improve change detection performance and that its importance increases with scene complexity. We note that these findings may be specific to unfamiliar situations such as those generated routinely in studies of change detection. In two questionnaire studies, we demonstrate that when (...) participants consider real world scenarios such as driving, people are well aware that the intention to detect changes improves detection performance, especially in complex scenes. We suggest several reasons why change detection findings like Beck et al.’s do not generalize to real world situations. More broadly, we suggest a possible way to bridge the gap between lab and life. (shrink)

Change blindness is the striking failure to see large changes that normally would be noticed easily. Over the past decade this phenomenon has greatly contributed to our understanding of attention, perception, and even consciousness. The surprising extent of change blindness explains its broad appeal, but its counterintuitive nature has also engendered confusions about the kinds of inferences that legitimately follow from it. Here we discuss the legitimate and the erroneous inferences that have been drawn, and offer a set of requirements (...) to help separate them. In doing so, we clarify the genuine contributions of change blindness research to our understanding of visual perception and awareness, and provide a glimpse of some ways in which change blindness might shape future research. (shrink)

In a series of three experiments, we explored the nature of implicit representations in change blindness . Using 3 × 3 letter arrays, we asked subjects to locate changes in paired arrays separated by 80 ms ISIs, in which one, two or three letters of a row in the second array changed. In one testing version, a tone followed the second array, signaling a row for partial report . In the other version, no PR was required. After Ss reported whether (...) a change had been detected and the PR had been completed , they were asked to identify a degraded letter trigram that was either novel, or from a previously shown row . Our findings indicate that when CB occurs, both the pre-change and post-change stimulus information primes despite its unavailability to consciousness. Surprisingly, findings also indicate that when change detection occurs only the post-change information primes. (shrink)

Anxiety has been associated with enhanced unconscious processing of threat and attentional biases towards threat. Here, we focused on the phenomenology of perception in anxiety and examined whether threat-related material more readily enters anxious than non-anxious individuals’ awareness. In six experiments, we compared the stimulus exposures required for each anxiety group to become objectively or subjectively aware of masked facial stimuli varying in emotional expression. Crucially, target emotion was task irrelevant. We found that high trait-anxiety individuals required less sensory evidence (...) to become aware of the face targets. This anxiety-based difference was observed for fearful faces in all experiments, but with non-threat faces, it emerged only when these were presented among threatening faces. Our findings suggest a prominent role for affective context in high-anxiety individuals’ conscious perception of visual stimuli. Possible mechanisms underlying the influence of context in lowering awareness thresholds in anxious individuals are discussed. (shrink)

According to a popular strategy amongst economists and philosophers, in order to solve the problem of interpersonal utility comparisons, we have to look at how ordinary people make such comparisons in everyday life. The most recent attempt to develop this strategy has been put forward by Goldman in his “Simulation and Interpersonal Utility” (Ethics 4:709–726, 1995). Goldman claims, first, that ordinary people make interpersonal comparisons by simulation and, second, that simulation is reliable for making interpersonal comparisons. In this paper, I (...) focus on Goldman’s latter claim. After updating Goldman’s account of how ordinary people make interpersonal comparisons in the light of Goldman’s newest formulation of his simulation theory of mental ascription (Goldman, Simulating Minds. Oxford University Press, Oxford, 2006), I develop and assess Goldman’s arguments in favour of the reliability of simulation for interpersonal comparisons. I argue that, under certain conditions, there may be room for a scientifically acceptable solution to the problem of interpersonal utility comparisons. (shrink)

Large changes that occur in clear view of an observer can become difficult to notice if made during an eye movement, blink, or other such disturbance. This change blindness is consistent with the proposal that focused visual attention is necessary to see change, with a change becoming difficult to notice whenever conditions prevent attention from being automatically drawn to it. -/- It is shown here how the phenomenon of change blindness can provide new results on the nature of visual attention, (...) including estimates of its capacity and the extent to which it can bind visual properties into coherent descriptions. It is also shown how the resultant characterization of attention can in turn provide new insights into the role that it plays in the perception of scenes and events. (shrink)

How must experience of time be structured in time? In particular, does the following principle, which I will call inheritance, hold: for any temporal property apparently presented in perceptual experience, experience itself has that same temporal property. For instance, if I hear Paul McCartney singing ‘Hey Jude’, must my auditory experience of the ‘Hey’ itself precede my auditory experience of the ‘Jude’, or can the temporal order of these experiences come apart from the order the words are experienced as having? (...) A number of recent authors (Phillips Experience and Time, ‘The Temporal Structure of Experience’, Soteriou ‘Perceiving Events’, Hoerl ‘“A Succession of Feelings, in and of Itself, is Not a Feeling of Succession”’, Rashbrook) claim, to paraphrase Martin (399), that inheritance best characterises how our temporal experience seems to initial reflective intuition. For this reason, Phillips takes the principle to form part of our naïve view of temporal experience. An opposing group of theorists object that inheritance is subject to empirical counter-example. This article surveys such challenges. Section 2 considers Grush's case against inheritance based on postdiction. Section 3 examines Watzl's anti-inheritance argument based on silencing effects. Finally, Section 4 explores a number of alleged counter-examples proposed by Lee (‘Temporal Experience and the Temporal Structure of Experience’). Section 1 provides essential background to the debate. (shrink)

The naïve view of temporal experience (Phillips, in: Lloyd D, Arstila V (eds) Subjective time: the philosophy, psychology, and neuroscience of temporality, forthcoming-a) comprises two claims. First, that we are perceptually aware of temporal properties, such as succession and change. Second, that for any temporal property apparently presented in experience, our experience itself possesses that temporal property. In his paper ‘Silencing the experience of change’ (forthcoming), Watzl argues that this second naïve inheritance thesis faces a novel counter-example in the form (...) of the striking motion silencing effects recently demonstrated by Suchow and Alvarez (Curr Biol 21(2):140–143, 2011). Here I clarify the form which any counter-example to naïve inheritance must take. I then explain how, on a plausible, rival ‘crowding’ interpretation of Suchow and Alvarez’s data, motion silencing poses no more of a threat to naïve inheritance than standard cases of change blindness. (shrink)

Colour has been shown to facilitate the recognition of scene images, but only when these images contain natural scenes, for which colour is ‘diagnostic’. Here we investigate whether colour can also facilitate memory for scene images, and whether this would hold for natural scenes in particular. In the first experiment participants first studied a set of colour and greyscale natural and man-made scene images. Next, the same images were presented, randomly mixed with a different set. Participants were asked to indicate (...) whether they had seen the images during the study phase. Surprisingly, performance was better for greyscale than for coloured images, and this difference is due to the higher false alarm rate for both natural and man-made coloured scenes. We hypothesized that this increase in false alarm rate was due to a shift from scrutinizing details of the image to recognition of the gist of the image. A second experiment, utilizing images without a nameable gist, confirmed this hypothesis as participants now performed equally on greyscale and coloured images. In the final experiment we specifically targeted the more detail-based perception and recognition for greyscale images versus the more gist-based perception and recognition for coloured images with a change detection paradigm. The results show that changes to images are detected faster when image-pairs were presented in greyscale than in colour. This counterintuitive result held for both natural and man-made scenes and thus corroborates the shift from more detailed processing of images in greyscale to more gist-based processing of coloured images. (shrink)

Kuhn and colleagues described a novel attentional misdirection approach to investigate overt and covert attention mechanisms in connection with inattentional blindness . This misdirection paradigm is valuable to study the temporal relationship between eye movements and visual awareness. Although, as put forth in this comment, the link between attentional misdirection and inattentional blindness needs to be developed further. There are at least four differences between the two paradigms which concern the conceptual aspects of the unexpected object and the methodological aspects (...) of the task design. This highlights the need for a broader theoretical framework incorporating inattentional blindness and overt and covert attention mechanisms. Two possible research lines focusing on the orienting attention research and the “selection-for-action” paradigm are discussed. (shrink)

The philosophical investigation of perceptual illusions can generate fruitful insights in the study of subjective time consciousness. However, the way illusions are interpreted is often controversial. Recently, proponents of the so-called dynamic snapshot theory have appealed to the Waterfall Illusion, a kind of motion aftereffect, to support a particular view of temporal consciousness according to which experience is structured as a series of instantaneous snapshots with dynamic qualities. This dynamism is meant to account for familiar features of the phenomenology of (...) time, such as succession, continuity, and change. Previous theories have typically appealed to a subjective present occupying an interval of time; that is, a “specious present.” I argue, through analysis of motion aftereffect illusions and the rare condition of akinetopsia, i.e. motion-blindness, that the Waterfall Illusion fails to support the dynamic snapshot theory as intended. Furthermore, I suggest that future theories of subjective time should see temporal phenomenology as the result of non-localised processes closely tied to the mechanism underlying consciousness generally. (shrink)

This study adopted a change detection task to investigate whether and how recognition intent affects the construction of orthographic representation in visual word recognition. Chinese readers and nonreaders detected color changes in radical components of Chinese characters. Explicit recognition demand was imposed in Experiment 2 by an additional recognition task. When the recognition was implicit, a bias favoring the radical location informative of character identity was found in Chinese readers , but not nonreaders . With explicit recognition demands, the effect (...) of radical location interacted with radical function and word frequency . An estimate of identification performance under implicit recognition was derived in Experiment 3. These findings reflect the joint influence of recognition intent and orthographic regularity in shaping readers’ orthographic representation. The implication for the role of visual attention in word recognition was also discussed. (shrink)

In this paper I critique the ethical implications of automating CCTV surveillance. I consider three modes of CCTV with respect to automation: manual, fully automated, and partially automated. In each of these I examine concerns posed by processing capacity, prejudice towards and profiling of surveilled subjects, and false positives and false negatives. While it might seem as if fully automated surveillance is an improvement over the manual alternative in these areas, I demonstrate that this is not necessarily the case. In (...) preference to the extremes I argue in favour of partial automation in which the system integrates a human CCTV operator with some level of automation. To assess the degree to which such a system should be automated I draw on the further issues of privacy and distance. Here I argue that the privacy of the surveilled subject can benefit from automation, while the distance between the surveilled subject and the CCTV operator introduced by automation can have both positive and negative effects. I conclude that in at least the majority of cases more automation is preferable to less within a partially automated system where this does not impinge on efficacy. (shrink)

Recently, a number of experiments have emphasized the degree to which subjects fail to detect large changes in visual scenes. This finding, referred to as “change blindness,” is often considered surprising because many people have the intuition that such changes should be easy to detect. Levin, Momen, Drivdahl, and Simons documented this intuition by showing that the majority of subjects believe they would notice changes that are actually very rarely detected. Thus subjects exhibit a metacognitive error we refer to as (...) “change blindness blindness.” Here, we test whether CBB is caused by a misestimation of the perceptual experience associated with visual changes and show that it persists even when the pre- and postchange views are separated by long delays. In addition, subjects overestimate their change detection ability both when the relevant changes are illustrated by still pictures, and when they are illustrated using videos showing the changes occurring in real time. We conclude that CBB is a robust phenomenon that cannot be accounted for by failure to understand the specific perceptual experience associated with a change. (shrink)

Recent research exploring phenomena such as change blindness, inattentional blindness, attentional blink and repetition blindness has revealed a number of counterintuitive ways in which apparently salient visual stimuli often go unnoticed. In fact, large majorities of subjects sometimes predict that they would detect visual changes that actually are rarely noticed, suggesting that people have strong beliefs about visual experience that are demonstrably incorrect. However, for other kinds of visual metacognition, such as picture memory, people underpredict performance. This paper describes two (...) experiments demonstrating that both these overpredictions of change detection, and underpredictions of visual memory can be linked with intuitions about the visual experience of different kinds of agents. Subjects predicted more visual change detection and poorer visual memory for mechanical representational systems when these were anthropomorphized using intentional terminology. (shrink)

Attention is often conceived as a gateway to consciousness . Although endogenous spatial attention may be independent of conscious perception , exogenous spatial orienting seems instead to be an important modulator of CP . Here, we investigate the role of auditory alerting in CP in normal observers. We used a behavioral task in which phasic alerting tones were presented either at unpredictable or at predictable time intervals prior to the occurrence of a near-threshold visual target. We find, for the first (...) time in neurologically intact observers, that phasic alertness increases CP, both objectively and subjectively. This result is consistent with evidence showing that phasic alerting can ameliorate the spatial bias exhibited by visual neglect patients . The alerting network may increase the activity of fronto-parietal networks involved in top-down amplification required to bring a stimulus into consciousness. (shrink)

Magicians use misdirection to prevent you from realizing the methods used to create a magical effect, thereby allowing you to experience an apparently impossible event. Magicians have acquired much knowledge about misdirection, and have suggested several taxonomies of misdirection. These describe many of the fundamental principles in misdirection, focusing on how misdirection is achieved by magicians. In this article we review the strengths and weaknesses of past taxonomies, and argue that a more natural way of making sense of misdirection is (...) to focus on the perceptual and cognitive mechanisms involved. Our psychologically-based taxonomy has three basic categories, corresponding to the types of psychological mechanisms affected: perception, memory, and reasoning. Each of these categories is then divided into subcategories based on the mechanisms that control these effects. This new taxonomy can help organize magicians' knowledge of misdirection in a meaningful way, and facilitate the dialog between magicians and scientists. (shrink)

A commentary on: Seeing changes: How familiarity alters our perception of change by Tovey, M., and Herdman, C. (2014). Vis. Cogn. 22, 214–238 .

We argue that embedded cognition provides an argument against Jaegwon Kim’s neural reduction of mental causation. Because some mental, or at least psychological processes have to be cast in an externalist way, Kim’s argument can be said to lead to the conclusion that mental causation is as safe as any other form of higher-level of causation.

Studies in cognitive psychology have shown that the deployment of visual attention operates under spatial limitations, rendering its assignment to multiple locations difficult or costly. This study explored whether this conventional understanding applies to human metaattention as well. I measured the spatial distribution of metaattention during viewing of natural scenes and found that participants believed they could attend to multiple locations simultaneously. Study 2 tested whether this tendency could be modified by information about the tendency to overestimation. After participants were (...) informed of this tendency toward overestimation with both verbal instruction and demonstrations of attentional blindness and blindness to these phenomena, the selectivity of metaattention increased. Study 3 demonstrated that participants overestimated their attentional abilities by comparing the metaattentional drawings and the actual behavioral performances of the same participants. These results were consistent with recent findings of metaattentional overestimation in change detection and suggested human insensitivity in monitoring attentional limitations. (shrink)

ABSTRACTThreat detection is crucial to survival. Studies using unnatural visual scene settings have shown that humans and primates are able to identify snakes more quickl...

Dreaming is often characterized as lacking high-order cognitive skills. In two studies, we test the alternative hypothesis that the dreaming mind is highly similar to the waking mind. Multiple experience samples were obtained from late-night REM sleep and waking, following a systematic protocol described in Kahan . Results indicated that reported dreaming and waking experiences are surprisingly similar in their cognitive and sensory qualities. Concurrently, ratings of dreaming and waking experiences were markedly different on questions of general reality orientation and (...) logical organization . Consistent with other recent studies , experiences sampled from dreaming and waking were more similar with respect to their process features than with respect to their structural features. (shrink)

A commentary on Dretske, "Change Blindness" (same journal issue). Dretske analyzes standard cases of change blindness as properly being difference blindness, since the eye is in saccade when the change occurs and so the change itself (the event of the change) is not seen. He considers two models of the phenomenon, the object model and the fact model, preferring the latter. In previous work, he had affirmed the object model. I reconsider its merits, first looking more closely at the notion (...) of differences and then making a case for seeing differences nonepistemically, or in Dretske’s “object mode.” I then consider some imagined cases that might rightly be classed as difference blindness in object mode, and offer a further taxonomy of various forms of difference blindness. The concluding section raises a fundamental question about the notion of seeing objects nonepistemically, or in a natural sensory (and hence nonconceptual) way. I do not deny the viability of the concept of nonepistemic perception in general, but I do question the notion that we are correctly thought to see spies and other types of individuals in natural sensory mode. That is, I question whether seeing spy-individuals is properly thought of as a natural sensory representational achievement. In this connection, I suggest that there is a tension in Dretske’s thought between nonepistemic seeing as he originally conceived it (1969) and the naturalized counterparts to that notion developed in his later works (1981, 1995). At least part of the explanation for this tension can be found in the differing methods and aims of his earlier and later work – the earlier work focusing on epistemology and philosophy of science, the later works on philosophy of psychology and a naturalized metaphysics of mind. (shrink)

A possible solution is offered to help resolve the “two times problem” regarding the veridical and illusory nature of time. First it is recognized that the flow of time is part of a wider array of temporal experiences referred to as manifest time, all of which need to be reconciled. Then, an information gathering and utilizing system model is used as a basis for a view of manifest time. The model IGUS robot of Hartle that solves the “unique present” debate (...) is enhanced with veridical and illusory components of not only the flow of time but also the larger entity of manifest time, providing a dualistic IGUS robot that represents all of the important temporal experiences. Based upon a variety of prior experiments, that view suggests that the veridical system is a reflection of accepted spacetime cosmologies and through natural selection begets the illusory system for functional purposes. Thus, there are not two opposing times, one outside and one inside the cranium. There is just one fundamental physical time which the brain developed, now possesses and is itself sufficient for adaption but then enhances. The illusory system is intended to provide a more satisfying experience of physical time, and better adaptive behavior. Future experiments to verify that view are provided. With a complete veridical system of temporal experiences there may be less need to reify certain temporal experiences so that the two times problem is less of a problem and more of a phenomenon. (shrink)

There is a long standing debate as to whether or not time is ‘real’ or illusory, and whether or not human time is a direct reflection of physical time. Differing spacetime cosmologies have opposing views. Exactly what human time entails has, in our opinion, led to the failure to resolve this ‘two times’ problem. To help resolve this issue we propose a dualistic model of human time in which each component has both an illusory and non-illusory aspect. With the dualistic (...) model we are able to provide experimental tests for all of the human time assertions of 10 chosen spacetime cosmologies. The illusory aspect of the ‘present,’ i.e. a ‘unique present’ was confirmed. An information gathering and utilizing system was constructed using a virtual reality apparatus allowing the observer to experientially roam back and forth along the worldline ad lib. The phenomenon of ‘change’ was experimentally found to be illusory at high frequency observation and non-illusory at low frequency observation, the latter phenomenon coinciding with ‘change’ referred to in the ‘Order of Time’ and ‘Relativity Refounded’ views. Additional experiments are presented indicating that both motion and temporality are dualistic. In sum, the dualistic model of human time allows for the existence of both illusory and non-illusory aspects of human time that are not in conflict with one another. It also provides experimental evidence for various spacetime cosmological assertions regarding human time. (shrink)

Perceptual completion fills the gap for discrete perception to become continuous. Similarly, dynamic perceptual completion provides an experience of dynamic continuity. Our recent discovery of the ‘happening’ element of DPC completes the total experience for dynamism in the flow of time. However, a phenomenological explanation for these experiences is essential. The Snapshot Hypotheses especially the Dynamic Snapshot View provides the most comprehensive explanation. From that understanding the ‘two times’ problem can be addressed. The static time of spacetime cosmologies has been (...) irreconcilable with the dynamic FOT. Dismissing the FOT as an illusion is unsatisfactory. Therefore, we provide four hypotheses for the TTP.1) Since cosmological static time demands that all events are discrete, DPC elements for dynamism should likewise be expected to be discrete and accounted for by a snapshot phenomenology such as the DSV. 2) If temporality can be demonstrated to be similar to apparent motion by being a snapshot phenomenon and not demanding temporal extension it would confirm the DSV and permit reconciliation with static time. 3) If the ‘present moment’ is subjective as static time theories suggest, it should be possible experimentally for an observer to choose his own ‘present’ by moving to various points in the past with the aid of virtual reality. 4) If dynamism e.g. motion can be precluded without significant information loss or violating physics principles it is a cognitive add-on, thereby contradicting non-static time theories which suggest that time is ‘real.’ We confirm those hypotheses. (shrink)

Attentional scanning was studied in anxious and non-anxious participants, using a modified change detection paradigm. Participants detected changes in pairs of emotional scenes separated by two task irrelevant slides, which contained an emotionally valenced scene and a visual mask. In agreement with attentional control theory, change detection latencies were slower overall for anxious participants. Change detection in anxious, but not non-anxious, participants was influenced by the emotional valence and exposure duration of distractor scenes. When negative distractor scenes were presented at (...) subliminal exposure durations, anxious participants detected changes more rapidly than when supraliminal negative scenes or subliminal positive scenes were presented. We propose that for anxious participants, subliminal presentation of emotionally negative distractor scenes stimulated attention into a dynamic state in the absence of attentional engagement. Presentation of the same scenes at longer exposure times was accompanied by conscious awareness, attentional engagement, and slower change detection. (shrink)

Change blindness illustrates a remarkable limitation in visual processing by demonstrating that substantial changes in a visual scene can go undetected. Because these changes can ultimately be detected using top–down driven search processes, many theories assign a central role to spatial attention in overcoming change blindness. Surprisingly, it has been reported that change blindness can occur during blink-contingent changes even when observers fixate the changing location [O’Regan, J. K., Deubel, H., Clark, J. J., & Rensink, R. A. . Picture changes (...) during blinks: Looking without seeing and seeing without looking. Visual Cognition, 7, 191–212]. However, eye blinks produce a transient disruption of vision that is independent of any associated changes in the retinal image. We determined whether these ‘attentive blank stares’ could occur in the absence of blink-mediated visual suppression. Using a flicker change-blindness paradigm we confirm that despite direct attentive fixations, obvious scene changes often remain undetected. We conclude that change detection involves object or feature based attentional mechanisms, which can be ‘misdirected’ despite the allocation of spatial attention to the position of the change. (shrink)