Spatiotemporal Form Integration: Sequentially presented inducers can lead to representations of stationary and rigidly rotating objects

Abstract

Objects in the world are often occluded and in motion. The visible fragments of such objects are revealed at different times and locations in space. To form coherent representations of the surfaces of these objects, the visual system must integrate local form information over space and time. We introduce a new illusion in which a rigidly rotating square is perceived on the basis of sequentially presented Pacman inducers. The illusion highlights two fundamental processes that allow us to perceive objects whose form features are revealed over time: Spatiotemporal Form Integration (STFI) and Position Updating. STFI refers to the spatial integration of persistent representations of local form features across time. Position updating of these persistent form representations allows them to be integrated into a rigid global motion percept. We describe three psychophysical experiments designed to identify spatial and temporal constraints that underlie these two processes and a fourth experiment that extends these findings to more ecologically valid stimuli. Our results indicate that although STFI can occur across relatively long delays between successive inducers (i.e., greater than 500 ms), position updating is limited to a more restricted temporal window (i.e., ~300 ms or less) and to a confined range of spatial (mis)alignment. These findings lend insight into the limits of mechanisms underlying the visual system's capacity to integrate transient, piecemeal form information and support coherent object representations in the ever-changing environment.

Extrastriate Visual Areas Integrate Form Features over Space and Time to Construct Representations of Stationary and Rigidly Rotating Objects

“…However, because we are mobile beings and objects around us are often in motion among other objects, the locations and times at which surface fragments become visible to us is typically in flux. Behavioral research has demonstrated that perceptual representations of such objects, whether they are stationary (Kojo, Liinasuo, & Rovamo, 1993), translating (Kellman & Shipley, 1991), or rigidly rotating (McCarthy, Strother, & Caplovitz, Under Review), can be formed on the basis of the integration of local form information across space and time. Despite the importance of such spatiotemporal integration processes, relatively little is known about the neural circuitry that supports them.…”

“…Instead, the visual system must maintain local form representations that persist when the items are no longer visible, so that they can be integrated with subsequently visible sources of information—STFI (Kojo et al, 1993; McCarthy et al, Under Review). While the mechanisms underlying spatial form integration, including processes such as modal and amodal completion, are relatively well understood (De Weerd, Desimone, & Ungerleider, 1996; Mendola, Dale, Fischl, Liu, & Tootell, 1999; Merigan, 1996; Murray et al, 2002; Pastor-Bernier, Tremblay, & Cisek, 2012; Pasupathy & Connor, 1999; Peterhans & von der Heydt, 1989; Peterhans, Von der Heydt, & Baumgartner, 1986; von der Heydt & Peterhans, 1989; von der Heydt, Peterhans, & Baumgartner, 1984), many questions about the neural processes that support STFI remain unanswered.…”

“…In the case of a rotating object, STFI alone will lead to a stationary deformed figure (Figure 1B, bottom right) whose integrated shape is inconsistent with the object’s veridical shape (Kellman & Shipley, 1991; McCarthy et al, Under Review). In order to represent the true shape of the object, the positions of previously visible form information need to be updated and matched with currently visible form cues such that the resulting percept will be of a rigidly moving object—Position Updating 1 (Palmer, Kellman, & Shipley, 2006).…”

“…Here we focus on the special case of motion of a rigidly rotating object. Specifically, if the angular displacement is small enough that features can be matched across successive inducers, this change is interpreted as motion such that a rigidly rotating square is perceived (McCarthy et al, Under Review). Indeed, there is a wealth of behavioral evidence demonstrating that shapes of translating and rigidly rotating objects can be perceived (Agaoglu, Herzog, & Ogmen, 2012; Helmholtz, 1867/1925; Kellman & Shipley, 1991; McCarthy et al, Under Review; Otto, Ogmen, & Herzog, 2009; Palmer, Kellman, & Shipley, 2006).…”

“…Specifically, if the angular displacement is small enough that features can be matched across successive inducers, this change is interpreted as motion such that a rigidly rotating square is perceived (McCarthy et al, Under Review). Indeed, there is a wealth of behavioral evidence demonstrating that shapes of translating and rigidly rotating objects can be perceived (Agaoglu, Herzog, & Ogmen, 2012; Helmholtz, 1867/1925; Kellman & Shipley, 1991; McCarthy et al, Under Review; Otto, Ogmen, & Herzog, 2009; Palmer, Kellman, & Shipley, 2006). In some of these instances the analysis of local motion information likely plays an important role in generating such percepts (Agaoglu et al, 2012; Helmholtz, 1867/1925; Kellman & Cohen, 1984; Kellman & Shipley, 1991; Otto et al, 2009; Palmer & Kellman, 2014; Palmer et al, 2006).…”