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When Predictions Fail: Correction for Extrapolation in the Flash-Grab Effect

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When Predictions Fail: Correction for Extrapolation in the Flash-Grab Effect Journal of Vision (2019) 19(2):3, 1–11 1 When predictions fail: Correction for extrapolation in the flash-grab effect Melbourne School of Psychological Sciences, Tessel Blom University of Melbourne, Melbourne, Australia $ Melbourne School of Psychological Sciences, Qianchen Liang University of Melbourne, Melbourne, Australia $ Melbourne School of Psychological Sciences, University of Melbourne, Melbourne, Australia Helmholtz Institute, Department of Experimental # Hinze Hogendoorn Psychology, Utrecht University, Utrecht, The Netherlands $ Motion-induced position shifts constitute a broad class of visual illusions in which motion and position signals Introduction interact in the human visual pathway. In such illusions, the presence of visual motion distorts the perceived A broad class of visual illusions demonstrate that positions of objects in nearby space. Predictive motion and position signals interact in the human mechanisms, which could contribute to compensating visual pathway. In such illusions, the presence of visual for processing delays due to neural transmission, have motion distorts the perceived positions of objects in been given as an explanation. However, such nearby space, causing motion-induced position shifts. mechanisms have struggled to explain why we do not The most-studied illusion in this category is probably usually perceive objects extrapolated beyond the end of their trajectory. Advocates of this interpretation have the flash-lag effect (Nijhawan, 1994), in which a proposed a ‘‘correction-for-extrapolation’’ mechanism to stimulus is flashed next to (and aligned with) a moving explain this: When the object motion ends abruptly, this object. The result is that the flash appears to lag behind mechanism corrects the overextrapolation by shifting the position of the moving object. In the related flash- the perceived object location backwards to its actual drag illusion, an object flashed adjacent to a moving location. However, such a mechanism has so far not texture is mislocalized in the direction of that texture’s been empirically demonstrated. Here, we use a novel motion (Whitney & Cavanagh, 2000a). Similarly, when version of the flash-grab illusion to demonstrate this motion is presented within a stationary patch, the mechanism. In the flash-grab effect, a target is flashed perceived position of that patch is shifted in the on a moving background that abruptly changes direction, direction of that motion (e.g., Anstis, 1989; De Valois leading to the mislocalization of the target. Here, we & De Valois, 1991; Ramachandran & Anstis, 1990). manipulate the angle of the direction change to Transient changes in an object’s visual properties (e.g., dissociate the contributions of the background motion size or color) are perceived to occur further along the before and after the flash. Consistent with previous object’s trajectory than they actually do (Cai & Schlag, reports, we observe that perceptual mislocalization in 2001), an effect that is sometimes dubbed the feature- the flash-grab illusion is mainly driven by motion after flash lag or the flash-jump. In the Fr hlich effect, the the flash. Importantly, however, we reveal a small but o¨ consistent mislocalization component in the direction initial position of an object that suddenly appears in opposite to the direction of the first motion sequence. motion is perceived as being shifted in the direction of This provides empirical support for the proposed its motion (Fro¨hlich, 1924; Kirschfeld & Kammer, correction-for-extrapolation mechanism, and therefore 1999). Finally, in the related flash-grab effect, an object corroborates the interpretation that motion-induced flashed on a moving background when that back- position shifts might result from predictive interactions ground unexpectedly changes direction is mislocalized between motion and position signals. in the background’s subsequent direction of motion (Cavanagh & Anstis, 2013). Citation: Blom, T., Liang, Q., & Hogendoorn, H. (2019). When predictions fail: Correction for extrapolation in the flash-grab effect. Journal of Vision, 19(2):3, 1–11, https://doi.org/10.1167/19.2.3. https://doi.org/10.1167/19.2.3Received October 8, 2018; published February 6, 2019 ISSN 1534-7362 Copyright 2019 The Authors Downloaded from jov.arvojournals.org on 02/08/2019This work is licensed under a Creative Commons Attribution 4.0 International License. Journal of Vision (2019) 19(2):3, 1–11 Blom, Liang, & Hogendoorn 2 The neural basis of these illusions has been hotly have revealed extrapolation mechanisms at various debated over the past decades, particularly in the stages of the visual hierarchy, including the retina context of the flash-lag effect. Different groups have (Berry, Brivanlou, Jordan, & Meister, 1999), lateral advocated explanations in extrapolation (Khurana, geniculate nucleus (Sillito, Jones, Gerstein, & West, Watanabe, & Nijhawan, 2000; Nijhawan, 1994), 1994), V1 (Jancke, Erlhagen, Scho¨ner, & Dinse, 2004), latency differences (Patel, Ogmen, Bedell, & Sampath, V4 (Sundberg, Fallah, & Reynolds, 2006), MT (Maus, 2000; Whitney & Murakami, 1998; Whitney, Muraka- Fischer, & Whitney, 2013), and in both monocular mi, & Cavanagh, 2000), attention (Baldo & Klein, and binocular populations (van Heusden, Harris, 1995; Brenner & Smeets, 2000), temporal averaging Garrido, & Hogendoorn, 2019). Using an electroen- (Krekelberg & Lappe, 2000) and postdiction (Eagle- cephalogram decoding approach, we recently showed man & Sejnowski, 2000). Initial attempts to reconcile that early cortical position signals are pre-activated these interpretations have largely focused on identify- ahead of predictably moving stimuli (Hogendoorn & ing whether these effects are temporal or spatial, that is, Burkitt, 2018a), and argued that within the framework identifying whether events are shifted in time or in of hierarchical predictive coding (Rao & Ballard, space (Eagleman & Sejnowski, 2002; Khurana et al., 1999), such extrapolation mechanisms would be 2000; Krekelberg & Lappe, 2001; Whitney, 2002). ubiquitous in the visual hierarchy (Hogendoorn & Later, Eagleman & Sejnowski (2007) proposed a Burkitt, 2018b). We have previously argued that EEG unified explanation in which local motion signals correlates of the flash-grab effect are detectable so collected over a brief time window are integrated to rapidly after presentation (;80 ms; Hogendoorn, bias instantaneous position judgments. The first Verstraten, & Cavanagh, 2015) that motion after the computational model uniting these effects was recently target could impossibly be processed on time to affect provided by Kwon, Tadin, and Knill (2015), which the (initial development of the) illusion. However, the explained motion and position interactions in terms of Fro¨hlich effect, in which there is no motion before the a Bayesian inference process. target event at all, indicates that motion prior to the Altogether there seems to be consensus that event is not necessary for mislocalization. This seems motion-induced position shifts result from an inter- to undermine an explanation in extrapolation, except action between position signals and motion signals. In that the instantaneous velocity signal present concur- particular, the importance of motion after the event is rently with the target has been argued to be sufficient clear: in the flash-lag effect, there is no illusion without to drive extrapolation mechanisms (Nijhawan, 2008). motion after the flash (Eagleman & Sejnowski, 2000; This was corroborated by a study showing that eye Maus & Nijhawan, 2009), and the same is true for the movements made to a very briefly presented moving flash-grab effect (Cavanagh & Anstis, 2013), and by target are targeted at the extrapolated position of that definition for the Fro¨hlich effect (Fro¨hlich, 1924). target, in a place where the target is never presented There is, however, still some debate surrounding how (Quinet & Goffart, 2015). More recently, we demon- long after an event motion signals are integrated to strated that the same is true when human observers influence the perceived position of that event: pro- make saccadic eye movements to a target whose posed values range from up to 50 ms following the position is shifted by the flash-grab effect: observers event (Whitney et al., 2000), 80 ms (Eagleman & make saccades to the extrapolated position of the Sejnowski, 2000), 150 ms (Brenner & Smeets, 2000), target (van Heusden, Rolfs, Cavanagh, & Hogen- 175 ms (Maus & Nijhawan, 2006), 200 ms (Cavanagh doorn, 2018). & Anstis, 2013; Kwon et al., 2015), all the way up to The degree to which motion before an event affects 500 ms (Krekelberg & Lappe, 1999, 2001). Similarly, the perceived position of that event is therefore still in the related flash-drag effect, in which a static flash is unclear. Indeed, even the role of static stimuli prior to mislocalized by presentation on or near a moving the flash-lag stimulus is disputed (Chappell & Hine, texture, motion signals within a certain interval 2004; Whitney & Cavanagh, 2000b). An additional around the flash onset time affect the perceived point of contention is the role of abrupt transients, location of the flash. The impact of motion signals such as those caused by the appearance or disap- within this interval is skewed towards the time after pearance of an object. Eagleman and Sejnowski the flash (Durant & Johnston, 2004; Murai & (2000) have argued that such transients reset the Murakami, 2016; Roach & McGraw, 2009). integration window, destroying neural traces of Theroleofmotionbefore
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