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Change Blindness their eye movements with eye trackers. During viewing, sudden changes were made to the dis- Walter T. Herbranson play and participants were asked to search for Whitman College, Walla Walla, WA, USA them. For example, an object in the scene might change color, change location, or disappear entirely. Changes that happened during an eye Definition saccade were more difficult to detect than those occurring during a fixation. Even prominent Change blindness is a phenomenon of visual changes encompassing a large portion of the attention in which changes to a visual scene may screen frequently went unnoticed if they hap- go unnoticed under certain circumstances, despite pened while the viewer’s eyes were in motion. being clearly visible and possibly even in an Subsequent research using different methods attended location. For example, the appearance showed that this kind of failure to detect changes of an object might not be noticed if it coincides is not limited to eye movements; change blindness with a disruption of visual continuity such as a can occur under a wide variety of conditions and flicker or an eye movement. Change blindness is at any time. For example, in the flicker task, one of an example of a striking limitation to visual atten- the most commonly used methods of investigating tion and indicates that visual representations are change blindness, participants search for a differ- more sparsely detailed than would sometimes be ence between two sequentially alternating visual assumed. The phenomenon can occur under a scenes that are identical save for a single feature wide array of circumstances, as well as in multiple (Rensink et al. 1997). If the scenes alternate sensory modalities, and has been demonstrated in instantaneously, with one image or the other some nonhuman animals. always visible, the change is usually seen quickly and effortlessly. Participants often report that the change “pops out” at them. On the other hand, if a Introduction short inter-stimulus interval (ISI) is inserted between each image, during which the screen is The first experimental investigations of change blank, the change is much more difficult to iden- blindness were of saccade-contingent changes: tify and requires an active, location-to-location changes that occur at the same time as eye move- search. Consequently, accuracy is worse, and ments. McConkie and Currie (1996), for example, latency to identify the change is longer. The had human participants view photographic dis- flicker task is particularly appealing to experimen- plays on a computer screen while monitoring tal psychologists because it allows them to easily

© Springer Nature Switzerland AG 2019 J. Vonk, T. K. Shackelford (eds.), Encyclopedia of Animal Cognition and Behavior, https://doi.org/10.1007/978-3-319-47829-6_1358-1 2 Change Blindness isolate and manipulate specific aspects of a has been done on these nonvisual equivalents of change, such as its size, location, or salience. change blindness, their existence would seem to The method also establishes the practical impor- suggest that change blindness could be due to a tance of change blindness, by showing that general nonmodality specific feature of attention. change blindness can occur at virtually any time, Research programs on change blindness carry regardless of what the participant is doing or some important implications for cognitive science where she is looking. The earlier demonstrations and our understanding of how we experience the of saccade-contingent change blindness world around us. While our momentary experi- constrained it to the short moments of time when ences during visual fixation may be quite detailed, the eyes are in motion. very little of that detail is maintained from one While the flicker task has been the most widely view to the next. Instead, the visual memory that used procedure for studying change blindness, persists from moment to moment is quite sparse, other methods have emerged that show the same consisting of little more than the meaning or gist pattern of results and illustrate that change blind- of a scene (Simons and Levin 1997). Thus, we fail ness can occur under widely varying conditions. to notice many feature-level changes because the For example, one method is similar to the flicker representations of those initial features are transi- task, in that participants attempt to identify tory and do not persist across the change. Never- changes in alternating images. However, instead theless, the details that are preserved appear to be of including an ISI to induce a global visual dis- sufficient to allow people to interact with a com- ruption, a set of small local disturbances plex world quite successfully, at least under most (“mudsplashes”) are superimposed onto the everyday circumstances. image at the moment of change (O’Regan et al. 1999). These mudsplashes are located so as not to obscure the change, but their presence neverthe- Change Blindness in Nonhuman Animals less makes it more difficult for participants to identify the difference between images. Thus, If change blindness is in fact a wide-ranging gen- the procedure illustrates that a global visual dis- eral consequence of sparsely detailed representa- ruption (as in the flicker task) is not necessary for tions of visual scenes, we might expect to see the change blindness to occur. Yet another method same phenomenon in some nonhuman animals uses gradual changes to produce change blind- that have similar visual systems. Indeed recent ness. In this method, two images are prepared research has shown predictable change detection that are identical save for one feature (such as failures in nonhuman animals using methods pat- the presence, location, or color of an object). terned after those originally developed to investi- One image is presented initially, but gradually gate change blindness in humans. dissolves into the other over the course of several Primates, of course, are closely related to seconds, and participants are asked to search for humans and have visual abilities that are compa- and identify the change (Simons et al. 2000). In rable in many ways. Thus, they make a logical this case, there is no visual disruption at all, and population for initial comparative research into yet participants often fail to notice the change, change blindness. Tomonaga and Imura (2015) especially if the rate of change is slow. used a variant of the flicker paradigm to study Not only can change blindness be produced by change blindness in chimpanzees and humans. a widely varying collection of laboratory proce- They presented alternating displays consisting of dures, there appear to be parallels in other sensory several line drawings on a CRT monitor in a task modalities. Using parallel methods, researchers inspired by the flicker paradigm. On each trial, have shown that people can be made to fail to one of those line drawings changed between alter- detect changes in auditory (Gregg and Samuel nating displays by either shifting position, chang- 2008), tactile (Gallace et al. 2007), and olfactory ing shape, or appearing/disappearing, and (Sela and Sobel 2010) stimuli. While less research chimpanzees were trained to touch the location Change Blindness 3 of the line drawing that changed. As in other participants. Accuracy remained better than implementations of the flicker task, some trials chance however, showing that pigeons were still included a blank field that appeared at the time capable of correctly identifying changes on some of a change, producing a global disruption of ISI trials. Subsequent research in the same lab visual continuity. Inclusion of those blank fields (Herbranson and Jeffers 2017) used the same led chimpanzees (like humans) to make more methodology to demonstrate change blindness errors and to respond more slowly to all three for color changes, a potentially more subtle vari- kinds of changes, indicating that change detection ety of change. Again, pigeons were less likely to was more difficult. detect a change if an ISI was present. Further- Cavanaugh and Wurtz (2002) used a similar more, change blindness in pigeons appears to be approach to study change blindness for motion affected by some of the same factors that affect change in macaques. Their monkeys viewed sev- change blindness in humans and in the same way. eral fields of moving dots on a display, one of Specifically, the magnitude of impairment caused which could change its direction of movement. by visual disruption depends on both the duration Monkeys were then rewarded for making an eye of an ISI and the salience of the change movement in the direction of the field that had (Herbranson 2015; Herbranson and Davis 2016). changed its direction of movement (or for not Whereas the flicker task produces change making an eye movement if no change had blindness via a global visual disruption, recall occurred). As with other change blindness tasks, that such a disruption is not necessary in humans, they included a global visual disruption on some who also show change blindness for gradual trials by presenting a brief blank field at the onset of changes that involve no visual disruption at all. the change. Change detection accuracy was Hagmann and Cook (2013) showed that this is impaired on those trials that featured a blank field, also the case for pigeons. They trained birds to a standard change blindness effect. Accuracy on detect continuous, gradual changes in brightness blank field trials improved if the location of the on a computer display using a go/no-go procedure. change was cued ahead of time, indicating that Pigeons viewed a colored rectangle that was either monkeys were still capable of detecting those constant or continuously changing in brightness. changes, and indeed could strategically use infor- Pecks on constant-brightness trials were reinforced mation to attenuate the effects of change blindness. on a VI schedule, and pecks on changing- Pigeons are more distantly related to humans, brightness trials resulted in a timeout. Birds but have excellent visual acuity and have long suppressed pecking on changing trials, but took been used to study visual attention in comparative longer to do so when the rate of change was slower. psychology. Herbranson et al. (2014) used a ver- Thus, more gradual changes were more difficult to sion of the flicker paradigm to study pigeons’ detect, as they are for humans. Again this shows ability to detect changes in a visual display. that changes may go unnoticed, even when there is Birds viewed alternating collections of features no disruption of visual continuity to obscure the (up to eight lines of varying orientations) pro- change. In the context of the previously described jected onto three response keys in an operant comparative research, it also shows that change chamber. One of the line features present on one blindness in pigeons is not tied to one specific response key appeared and vanished across pre- laboratory procedure such as the flicker task. sentations, and after observing a required number of iterations, pecks to the location of the change were reinforced. Some trials contained an ISI Conclusion between successive displays (causing a global visual disruption) and other trials did not. Pigeons Change blindness has been a topic of considerable were less likely to peck the location of the change interest in cognitive psychology in recent decades. if an ISI was present, the same change blindness Research on humans indicates that it can occur in pattern seen in the flicker task with human a wide variety of situations, and consequently can 4 Change Blindness be studied using many different procedures. The References resulting collection of research tools includes sev- eral tasks such as the flicker paradigm that can be Cavanaugh, J., & Wurtz, R. (2002). Change blindness for readily adapted to study change blindness in non- motion in macaque monkey. Journal of Vision, 2(7), 16. Gallace, A., Tan, H. Z., & Spence, C. (2007). Do human animals. While only a small number of “mudsplashes” induce tactile change blindness? Atten- species have been tested and only a subset of the tion, Perception & Psychophysics, 69(4), 477–486. developed change blindness tasks have been Gregg, M. K., & Samuel, A. G. (2008). Change deafness adapted, the available results show striking paral- and the organizational properties of sounds. Journal of Experimental Psychology: Human Perception and Per- lels with the results produced by humans. formance, 34(4), 974–991. Change blindness research has thrived in part Hagmann, C. E., & Cook, R. G. (2013). Active change because it presents results that do not match most detection by pigeons and humans. Journal of Experi- people’s subjective perceptions. Our momentary mental Psychology: Animal Behavior Processes, 39, 383–389. visual experience appears detailed, even though Herbranson, W. T. (2015). Change blindness in pigeons that detail is transitory and does not persist across (Columba livia): The effects of change salience and views, and most people overestimate their ability timing. Frontiers in Psychology, 6, 1109. to detect changes (“change blindness blindness”; Herbranson, W. T., & Davis, E. T. (2016). The effect of display timing on change blindness in pigeons Levin et al. 2000). The existence of change blind- (Columba livia). Journal of the Experimental Analysis ness in nonhuman animals might initially seem of Behavior, 105,85–99. just as puzzling, given that vigilance and the abil- Herbranson, W. T., & Jeffers, J. S. (2017). Pigeons ity to quickly and accurately detect changes would (Columba livia) show change blindness in a color change detection task. Animal Cognition, 20, intuitively seem to have survival value for many 725–7379. animals. Simons and Levin (1997) propose that Herbranson, W. T., Trinh, Y. T., Xi, P. M., Arand, M. P., the sparsely detailed visual representations that Barker, M. S., & Pratt, T. H. (2014). Change detection give rise to change blindness may serve to provide and change blindness in pigeons (Columba livia). Jour- nal of Comparative Psychology, 128, 181–187. stability and continuity from moment to moment. Levin, D. T., Momen, N., Drivdahl, S. B., & Simons, D. J. Thus, one can have a detailed perceptual experi- (2000). Change blindness blindness: The meta- ence at any instant, but by preserving only those cognitive error of overestimating change-detection – components that are likely to be important, the ability. Visual Cognition, 7, 397 412. McConkie, G. W., & Currie, C. B. (1996). Visual stability relevant features in the next glance can be quickly across saccades while viewing complex pictures. Jour- matched up without the overwhelming task of nal of Experimental Psychology: Human Perception tracking and linking each and every minute detail. and Performance, 22(3), 563–581. ’ Presumably this logic would apply as well to O Regan, J. K., Rensink, R. A., & Clark, J. J. (1999). Change-blindness as a result of “mudsplashes”. Nature, nonhuman animals, who often have to solve the 398, 34. same perceptual problems as humans, with even Rensink, R. A., O’Regan, J. K., & Clark, J. J. (1997). To more limited neural resources. see or not to see: The need for attention to perceive changes in scenes. Psychological Science, 8, 368–373. Sela, L., & Sobel, N. (2010). Human olfaction: A constant state of change-blindness. Experimental Brain Research, Cross-References 205(1), 13–29. Simons, D. J., & Levin, D. T. (1997). Change blindness. – ▶ Attention Trends in Cognitive Sciences, 1(7), 261 267. ▶ Simons, D. J., Franconieri, S. L., & Reimer, R. L. (2000). Change Detection Change blindness in the absence of a visual disruption. ▶ Cognition Perception, 29, 1143–1154. ▶ Same/Different Learning Tomonaga, M., & Imura, T. (2015). Change they can’t see: ▶ Search Image Change blindness in chimpanzees during a visual search task. i-Perception, 6(2), 104–107. ▶ Short-Term Memory ▶ Visual Perception ▶ Visual Search ▶ Working Memory