Perceptual constraints on implicit learning of spatial context

If perspective views of an object in two orientations are displayed in alternation, observers will experience the object rotating back and forth in three-dimensional space. Rotational motion is perceived even though only two views are displayed and each view is two-dimensional. The results of 5 experiments converge on the conclusion that the perception of apparent rotational motion produces representations in visual memory corresponding to the spatial structure of the object along its arc of rotation. These representations are view-dependent, preserving information about spatial structure from particular perspectives, but do not preserve low-level perceptual details of the stimulus.     

Perceiving and Imagining Plato's Solids: The Generalized Cylinder in Spatial Organization of 3D Structures

The regular polyhedra, commonly known as the “Platonic solids”, are fundamental three-dimensional structures. It is known that the ease of imagining one of these solids, the cube, varies radically with its orientation to the vertical. We demonstrate the same variation for perception and imagination of all three of the simpler Platonic solids: The cube, octahedron, and tetrahedron. In orientations of the objects that are relatively easy to comprehend, the objects are generalized cylinders about the vertical. In the difficult orientations, the objects are antiprismatic about the vertical. The critical difference between these structures is that generalized cylinders have uniform orientations of edges and surfaces about an object axis while antiprisms have nonuniform orientations. These results support strongly the view that the orientations of objectfeatures are important in spatial organization, that humans are highly sensitive to objective forms of regularity in spatial organization, and that the generalized cylinder is a form of spatial regularity that people find simple.     

注意促进运动知觉判断的时间进程

本研究通过控制深度视觉线索, 分析3D SFM (structure from motion)知觉中的眼动特征, 探讨注意对SFM知觉判断的影响及其时间进程。结果显示, 有线索刺激比模糊刺激的判断更加快、更加肯定(百分比更高); 眼睛移动方向和微眼跳方向都分别与知觉判断的运动方向具有一致性; 微眼跳频次、峰速度和幅度也都分别表现出深度线索的促进效应。实验结果表明, SFM知觉过程大致分为速度计算和构建三维结构两个阶段; 注意对SFM知觉的调节作用主要发生在构建三维结构阶段; 注意从150 ms开始指向选择对象, 驻留持续约200 ms后, 从局部运动矢量流转移到整体运动方向的知觉判断。     

Attention and depth perception

The Necker cube is a line drawing with two possible solutions in depth perception. The process of interpreting a two-dimensional line drawing as a three-dimensional object was investigated using the Necker cube. Attention was directed to a local feature of a briefly presented cube, ie an angle at a vertex. The attended angle was perceived as a front part of the cube and other parts were interpreted so as to match this interpretation. Results show that the local feature to which attention was directed was interpreted first and then global features and other local features were interpreted so as to agree with the local feature interpreted initially. This suggests that the three-dimensional interpretation of the line drawing was made sequentially from the local feature to global structures.     

No symmetry advantage when object matching involves accidental viewpoints

The presupposed advantage of symmetrical objects over asymmetrical objects was investigated in an object matching task, using accidental and non-accidental viewpoints. In addition, the accidental views could be symmetric or asymmetric. When two non-accidental views were presented, symmetrical objects were matched faster than asymmetrical objects. When an accidental view was presented first (followed by a non-accidental view), the matching of symmetrical objects was equal to that of asymmetrical objects. When a non-accidental view was presented first (followed by an accidental view), matching was again equal for the symmetrical and asymmetrical objects, although much faster compared with the opposite sequence of presented views. No effects of image symmetry in the accidental viewpoints were found. Apparently, the advantage of symmetrical objects over asymmetrical objects is only present in object matching when 3-D object structures are visible.     

Aligning the eye to the actively or passively positioned hand

Observations were made of the reversal rate of a three-dimensional skeletal cube as a function of observing condition and state of rest or motion of the cube. Perspective reversal rate of the stationary three-dimensional cube is greater than direction reversal rate of the same cube set in motion. Reversal rate of the rotating cube drops with rest, replicating a similar finding with the Necker cube. Comparisons are made with the rotating trapezoidal window illusion. nt]mis|The author is most grateful to Marshall P. Smith, Chairman of the Psychology Department of Trenton State College, for his aid in securing space and college students, and to David L. Hoats, of the Johnstone Research Department, for wiring the apparatus.     

Dynamic object perception by pigeons.

Three experiments examined pigeon discrimination of computer-generated three-dimensional (3-D) projections of cube and pyramid objects. Four pigeons were tested using a go/no-go procedure involving static and dynamically rotating presentations of these stimuli. Transfer tests with different types of rotational and featural transformations suggested the pigeons may have used a 3-D representation of the objects as their primary means of performing the discrimination. The comparative implications for object and motion perception in animals are considered.     

Motion as a cue for viewpoint invariance

Natural face and head movements were mapped onto a computer rendered three-dimensional average of 100 laser-scanned heads in order to isolate movement information from spatial cues and nonrigid movements from rigid head movements (Hill & Johnston, 2001). Experiment 1 investigated whether subjects could recognize, from a rotated view, facial motion that had previously been presented at a full-face view using a delayed match to sample experimental paradigm. Experiment 2 compared recognition for views that were either between or outside initially presented views. Experiment 3 compared discrimination at full face, three-quarters, and profile after learning at each of these views. A significant face inversion effect in Experiments 1 and 2 indicated subjects were using face-based information rather than more general motion or temporal cues for optimal performance. In each experiment recognition performance only ever declined with a change in viewpoint between sample and test views when rigid motion was present. Nonrigid, face-based motion appears to be encoded in a viewpoint invariant, object-centred manner, whereas rigid head movement is encoded in a more view specific manner.     

The visual representation of three-dimensional, rotating objects.

Depth rotations can reveal new object parts and result in poor recognition of "static" objects (Biederman & Gerhardstein, 1993). Recent studies have suggested that multiple object views can be associated through temporal contiguity and similarity (Edelman & Weinshall, 1991; Lawson, Humphreys & Watson, 1994; Wallis, 1996). Motion may also play an important role in object recognition since observers recognize novel views of objects rotating in the picture plane more readily than novel views of statically re-oriented objects (Kourtzi & Shiffrar, 1997). The series of experiments presented here investigated how different views of a depth-rotated object might be linked together even when these views do not share the same parts. The results suggest that depth rotated object views can be linked more readily with motion than with temporal sequence alone to yield priming of novel views of 3D objects that fall in between "known" views. Motion can also enhance path specific view linkage when visible object parts differ across views. Such results suggest that object representations depend on motion processes.     

Demonstrations of spatiotemporal integration and what they tell us about the visual system

Five sets of displays are presented on the journal website to be viewed in conjunction with the text. We concentrate on the factors that give rise to the integration and disruption of the direction of apparent motion in two-dimensional and three-dimensional space. In the first set of displays we examine what factors contribute to the integration and disruption of apparent motion in the Ramachandran/Anstis clustered bistable quartets. In the second set we examine what factors give rise to the perception of the direction of motion in rotating two-dimensional wheels and dots. In the third and fourth sets we examine how the depth cues of shading and disparity contribute to the perception of apparent motion of opaque displays, and to the perception of rotating unoccluded displays, respectively. In the fifth set we examine how the depth cue of motion parallax influences the perception of apparent motion. Throughout, we make inferences about the roles which various parallel pathways and cortical areas play in the perceptions produced by the displays shown.     

Dynamic orientation cues decrease the viewpoint cost of mental rotation

Mental rotation, as a covert simulation of motor rotation, could benefit from spatial updating of object representations. We are interested in what kind of visual cue could trigger spatial updating. Three experiments were conducted to examine the effect of dynamic and static orientation cues on mental rotation, using a sequential matching task with three-dimensional novel objects presented in different views. Experiment 1 showed that a rotating orientation cue with constant speed reduced viewpoint costs in mental rotation. Experiment 2 extended this effect with a varied-speed rotating orientation cue. However, no such benefit was observed with a static orientation cue in Experiment 3. These findings indicated that a visually continuous orientation cue is sufficient to elicit spatial updating in mental rotation. Furthermore, there may be differences in the underlying mechanisms of spatial updating on the basis of constant-speed rotating cues and varied-speed rotating cues.     

Oxytocin enhances the perception of biological motion in humans

Evidence suggests that intranasally administered oxytocin modulates several social cognitive and emotional processes in humans. In this study, we investigated the effect of oxytocin on the perception of biological motion (a walking character) and nonbiological motion (a rotating shape). The participants were 20 healthy volunteers who observed moving dots embedded among a cloud of noise (mask) dots. Sensitivity (d ^’) for motion detection was determined after the administration of oxytocin and placebo. The results showed that oxytocin (relative to placebo) administration increased sensitivity to biological motion but not to nonbiological motion. These results suggest that oxytocin specifically modulates the perception of socially relevant stimuli.     

Combining motor and spatial affordance effects with the divided visual field paradigm

The affordance effect has been widely investigated employing various behavioral and brain-imaging techniques. Attempts to interpret the nature of the affordance effect led to two major views. Some researchers compare this kind of compatibility effect to the Simon effect, claiming abstract spatial association between the handle orientation of visually presented stimuli and the nearest response hand. Other authors advocate pure motor activation, during processing of visually presented tools without the involvement of spatial information. However, brain-imaging studies seem to agree that no action can be computed in the absence of spatial information. Taking the latter view into account, a divided visual field experiment was conducted, with the aim of crossing spatial and affordance correspondence effects. Overall, the results supported the view that motor and spatial information go hand in hand. Moreover, the data were in agreement with neuroimaging studies that show tool and affordance processing lateralization in the left hemisphere. The results are discussed in terms of neurophysiological data and brain mechanisms of perception and action.     

View combination: a generalization mechanism for visual recognition

We examined whether view combination mechanisms shown to underlie object and scene recognition can integrate visual information across views that have little or no three-dimensional information at either the object or scene level. In three experiments, people learned four “views” of a two dimensional visual array derived from a three-dimensional scene. In Experiments 1 and 2, the stimuli were arrays of colored rectangles that preserved the relative sizes, distances, and angles among objects in the original scene, as well as the original occlusion relations. Participants recognized a novel central view more efficiently than any of the Trained views, which in turn were recognized more efficiently than equidistant novel views. Experiment 2 eliminated presentation frequency as an explanation for this effect. Experiment 3 used colored dots that preserved only identity and relative location information, which resulted in a weaker effect, though still one that was inconsistent with both part-based and normalization accounts of recognition. We argue that, for recognition processes to function so effectively with such minimalist stimuli, view combination must be a very general and fundamental mechanism, potentially enabling both visual recognition and categorization.     

Visual representation of malleable and rigid objects that deform as they rotate

Most studies and theories of object recognition have addressed the perception of rigid objects. Yet, physical objects may also move in a nonrigid manner. A series of priming studies examined the conditions under which observers can recognize novel views of objects moving nonrigidly. Observers were primed with 2 views of a rotating object that were linked by apparent motion or presented statically. The apparent malleability of the rotating prime object varied such that the object appeared to be either malleable or rigid. Novel deformed views of malleable objects were primed when falling within the object's motion path. Priming patterns were significantly more restricted for deformed views of rigid objects. These results suggest that moving malleable objects may be represented as continuous events, whereas rigid objects may not. That is, object representations may be "dynamically remapped" during the analysis of the object's motion.     

Young Children's Self-Generated Object Views and Object Recognition

Two important and related developments in children between 18 and 24 months of age are the rapid expansion of object name vocabularies and the emergence of an ability to recognize objects from sparse representations of their geometric shapes. In the same period, children also begin to show a preference for planar views (i.e., views of objects held perpendicular to the line of sight) of objects they manually explore. Are children's emerging view preferences somehow related to contemporary changes in object name vocabulary and object perception? Children aged 18 to 24 months old explored richly detailed toy objects while wearing a head camera that recorded their object views. Both children's vocabulary size and their success in recognizing sparse three-dimensional representations of the geometric shapes of objects were significantly related to their spontaneous choice of planar views of those objects during exploration. The results suggest important interdependencies among developmental changes in perception, action, word learning, and categorization in very young children.     

Three-quarter views are subjectively good because object orientation is uncertain

Because the objects that surround us are three-dimensional, their appearance and our visual perception of them change depending on an object’s orientation relative to a viewpoint. One of the most remarkable effects of object orientation is that viewers prefer three-quarter views over others, such as front and back, but the exact source of this preference has not been firmly established. We show that object orientation perception of the threequarter view is relatively imprecise and that this impreciseness is related to preference for this view. Human vision is largely insensitive to variations among different three-quarter views (e.g., 45° vs. 50°); therefore, the three-quarter view is perceived as if it corresponds to a wide range of orientations. In other words, it functions as the typical representation of the object.     

What is Wrong with Sufficiency?

In this paper, I ask what is wrong with sufficiency. I formulate a generic sufficiency principle in relation to which I discuss possible problems for sufficientarianism. I argue against the arbitrariness–concern, that sufficiency theory need only to identify a possible space for determining a plausible threshold, and I argue against the high–low threshold dilemma concern, that multiple-threshold views can solve this dilemma. I then distinguish between currency-pluralist and currency-monist multiple-threshold views and test them against two different versions of the widely shared ‘ignorance of inequality objection’ to sufficientarianism—a benefit-driven and a burden-driven version. I argue that currency-pluralist sufficiency views are better capable of responding to the former than currency-monist views. However, I show that no existing sufficiency view can provide a plausible response to the burden-driven version. Hence, I conclude that the problem of unequal distribution of burdens above the thresholds represents an overlooked threat to the sufficiency view, in any version.

     

Object-based warping: an illusory distortion of space within objects

Visual objects are high-level primitives that are fundamental to numerous perceptual functions, such as guidance of attention. We report that objects warp visual perception of space in such a way that spatial distances within objects appear to be larger than spatial distances in ground regions. When two dots were placed inside a rectangular object, they appeared farther apart from one another than two dots with identical spacing outside of the object. To investigate whether this effect was object based, we measured the distortion while manipulating the structure surrounding the dots. Object displays were constructed with a single object, multiple objects, a partially occluded object, and an illusory object. Nonobject displays were constructed to be comparable to object displays in low-level visual attributes. In all cases, the object displays resulted in a more powerful distortion of spatial perception than comparable non-object-based displays. These results suggest that perception of space within objects is warped.