The effects of scene inversion on change blindness

In two experiments, participants searched for a difference between two views of a scene. In Experiment 1, the authors extended the change-blindness findings from previous work by R. A. Rensink, J. K. O'Regan, and J. J. Clark (1997), which used an experimenter-induced global transient, to a less artificial situation in which participants searched for a difference in a pair of photographic images presented simultaneously. To examine the idea that meaning-driven endogenous orienting was responsible for the previously observed advantage for changes in center-of-interest items, the authors inverted half of the image pairs. The advantage for center-of-interest items was replicated with upright displays, but it was completely eliminated by inversion, strongly supporting the role of meaning-driven endogenous orienting in this task. With flickering displays (Experiment 2), the center-of-interest effect was completely unaffected by inversion. The authors suggest that when change blindness is induced via flicker, scene modifications are typically found by stimulus-driven rather than by meaning-driven processes.     

Objects and attributes in divided attention: Surface and boundary systems

A series of experiments investigated concurrent discriminations of surface and nonsurface attributes, including color, brightness, texture, length, location, and motion. In all cases but one, results matched those previously reported: Interference occurred when two discriminations concerned different objects, but not when they concerned the same one. In the two-object case, interference was the same whether discriminations were similar (e.g., two surface discriminations) or different (e.g., one surface, one boundary). Such results support a model of visual attention in which separate visual subsystems are coordinated, converging to work on surface and boundary properties of the same selected object. A partial exception is color: For reasons that are unclear, color escapes twoobject interference except from other, concurrent surface discriminations     

The Effects of Scene Inversion on Change Blindness

In two experiments, participants searched for a difference between two views of a scene. In Experiment 1, the authors extended the change-blindness findings from previous work by R. A. Rensink, J. K. O'Regan, and J. J. Clark (1997), which used an experimenter-induced global transient, to a less artificial situation in which participants searched for a difference in a pair of photographic images presented simultaneously. To examine the idea that meaning-driven endogenous orienting was responsible for the previously observed advantage for changes in center-of-interest items, the authors inverted half of the image pairs. The advantage for center-of-interest items was replicated with upright displays, but it was completely eliminated by inversion, strongly supporting the role of meaning-driven endogenous orienting in this task. With flickering displays (Experiment 2), the center-of-interest effect was completely unaffected by inversion. The authors suggest that when change blindness is induced via flicker, scene modifications are typically found by stimulus-driven rather than by meaning-driven processes.     

Grasping with the eyes: The role of elongation in visual recognition of manipulable objects

Processing within the dorsal visual stream subserves object-directed action, whereas visual object recognition is mediated by the ventral visual stream. Recent findings suggest that the computations performed by the dorsal stream can nevertheless influence object recognition. Little is known, however, about the type of dorsal stream information that is available to assist in object recognition. Here, we present a series of experiments that explored different psychophysical manipulations known to bias the processing of a stimulus toward the dorsal visual stream in order to isolate its contribution to object recognition. We show that elongated-shaped stimuli, regardless of their semantic category and familiarity, when processed by the dorsal stream, elicit visuomotor grasp-related information that affects how we categorize manipulable objects. Elongated stimuli may reduce ambiguity during grasp preparation by providing a coarse cue to hand shaping and orientation that is sufficient to support action planning. We propose that this dorsal-stream-based analysis of elongation along a principal axis is the basis for how the dorsal visual object processing stream can affect categorization of manipulable objects.     

Hand selection for object grasping is influenced by recent motor history

Action selection processes such as those that underlie decisions about which hand to use for upcoming actions are fundamental to adaptive motor behavior. Previous research has shown that people grasp objects in ways that reflect anticipated task demands, as well as recent movement experience. However, very few studies have addressed the possible influence of recent motor history on hand selection. In the present study, participants grasped and placed objects using either their left or right hand. The results showed shorter response times to initiate successive actions when hand was repeated, even when those actions involved distinct grasp postures and object placement movements to distinct locations. Conversely, no such planning advantage was observed for repeated grasps for successive actions made with opposite hands. The findings are consistent with the idea that choices about which hand to use in the present are influenced by which hand was used in the recent past. When the same hand can be used for successive actions, planning is made more efficient, presumably because the motor parameters that specify which hand to use can be recalled from recent memory rather than formulated anew. The findings indicate that hand selection is sensitive to recent movement experience and provide novel support for computational efficiency accounts of motor history effects.     

A soft-contact model for computing safety margins in human prehension

The soft human digit tip forms contact with grasped objects over a finite area and applies a moment about an axis normal to the area. These moments are important for ensuring stability during precision grasping. However, the contribution of these moments to grasp stability is rarely investigated in prehension studies. The more popular hard-contact model assumes that the digits exert a force vector but no free moment on the grasped object. Many sensorimotor studies use this model and show that humans estimate friction coefficients to scale the normal force to grasp objects stably, i.e. the smoother the surface, the tighter the grasp. The difference between the applied normal force and the minimal normal force needed to prevent slipping is called safety margin and this index is widely used as a measure of grasp planning. Here, we define and quantify safety margin using a more realistic contact model that allows digits to apply both forces and moments. Specifically, we adapt a soft-contact model from robotics and demonstrate that the safety margin thus computed is a more accurate and robust index of grasp planning than its hard-contact variant. Previously, we have used the soft-contact model to propose two indices of grasp planning that show how humans account for the shape and inertial properties of an object. A soft-contact based safety margin offers complementary insights by quantifying how humans may account for surface properties of the object and skin tissue during grasp planning and execution.     

Coming to grips with weight perception: effects of grasp configuration on perceived heaviness

We investigated how changes in grasp configuration affect perceived heaviness in a weight discrimination task in which participants compared the weights of a series of test objects with the weight of a reference object. In different experiments, we varied the width of the grasp, the number of digits employed, the angle of the grasp surface, and the size of the contact area between the digits and the object. We show that objects are perceived to be lighter when lifting with (1) a wide grip in comparison with a narrow grip, (2) five digits in comparison with two digits, and (3) a large contact area in comparison with a small contact area. However, the angle of the contact surfaces did not influence perceived weight. We suggest that changes in central motor commands associated with grasp differences may influence perceived weight, at least under some conditions.     

Failures to see: attentive blank stares revealed by change blindness

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. (2000). 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.     

Change blindness and the primacy of object appearance

A large body of work suggests that the visual system is particularly sensitive to the appearance of new objects. This is based partly on evidence from visual search studies showing that onsets capture attention whereas many other types of visual event do not. Recently, however, the notion that object onset has a special status in visual attention has been challenged. For instance, an object that looms toward an observer has also been shown to capture attention. In two experiments, we investigated whether onset receives processing priority over looming. Observers performed a change detection task in which one of the display objects either loomed or receded, or a new object appeared. Results showed that looming objects were more resistant to change blindness than receding objects. Crucially, however, the appearance of a new object was less susceptible to change blindness than both looming and receding. We argue that the visual system is particularly sensitive to object onsets.     

Repetition blindness for novel objects

When visual stimuli (letters, words or pictures of objects) are presented sequentially at high rates (8–12 items/s), observers have difficulty in detecting and reporting both occurrences of a repeated item: This is repetition blindness. Two experiments investigated the effects of repetition of novel objects, and whether the representations bound to episodic memory tokens that yield repetition blindness are viewpoint dependent or whether they are object centred. Subjects were shown coloured drawings of simple three‐dimensional novel objects, and rate of presentation (Experiment 1) and rotation in depth (Experiment 2) were manipulated. Repetition blindness occurred only at the higher rate (105 ms/item), and was found even for stimuli differing in orientation. We conclude that object‐centred representations are bound to episodic memory tokens, and that these are constructed prior to object recognition operating on novel as well as known objects. These results are contrasted with those found with written materials, and implications for explanations of repetition blindness are considered.     

Change deafness and the organizational properties of sounds

Change blindness, or the failure to detect (often large) changes to visual scenes, has been demonstrated in a variety of different situations. Failures to detect auditory changes are far less studied, and thus little is known about the nature of change deafness. Five experiments were conducted to explore the processes involved in change deafness by measuring explicit change detection as well as auditory object encoding. The experiments revealed that considerable change deafness occurs, even though auditory objects are encoded quite well. Familiarity with the objects did not affect detection or recognition performance. Whereas spatial location was not an effective cue, fundamental frequency and the periodicity/aperiodicity of the sounds provided important cues for the change-detection task. Implications for the mechanisms responsible for change deafness and auditory sound organization are discussed.     

The Sound of Grasp Affordances: Influence of Grasp‐Related Size of Categorized Objects on Vocalization

Previous research shows that simultaneously executed grasp and vocalization responses are faster when the precision grip is performed with the vowel [i] and the power grip is performed with the vowel [ɑ]. Research also shows that observing an object that is graspable with a precision or power grip can activate the grip congruent with the object. Given the connection between vowel articulation and grasping, this study explores whether grasp‐related size of observed objects can influence not only grasp responses but also vowel pronunciation. The participants had to categorize small and large objects into natural and manufactured categories by pronouncing the vowel [i] or [ɑ]. As predicted, [i] was produced faster when the object's grasp‐related size was congruent with the precision grip while [ɑ] was produced faster when the size was congruent with the power grip (Experiment 1). The effect was not, however, observed when the participants were presented with large objects that are not typically grasped by the power grip (Experiment 2). This study demonstrates that vowel production is systematically influenced by grasp‐related size of a viewed object, supporting the account that sensory‐motor processes related to grasp planning and representing grasp‐related properties of viewed objects interact with articulation processes. The paper discusses these findings in the context of size–sound symbolism, suggesting that mechanisms that transform size‐grasp affordances into corresponding grasp‐ and articulation‐related motor programs might provide a neural basis for size‐sound phenomena that links small objects with closed‐front vowels and large objects with open‐back vowels.     

2～4岁儿童对"大""小"空间形容词词义掌握的研究

本研究以2～4儿童为研究对象。在自然实验条件下,通过精心设计的四项实验,得出结论：2岁儿童还未了解大小词义;2．5岁儿童能判别当前两同类物体的大小;3岁儿童能对两同类物体的大小相对性比较;4岁儿童能掌握不同类物体间大小的搭配;4岁儿童9成能掌握人与物间相对大小的匹配,但仅一半儿童掌握三个同类物体同时比较时大小相对关系,即4岁儿童还未对“大”“小”词义完全掌握。实验表明儿童掌握“大”“小”空间形容词是由易到难,由浅到深,由绝对禁止到相对灵活,由以自我为中心到以外界为中心。     

Form-based representation in the mental lexicon: priming (with) bound stem allomorphs in Finnish

A series of four visual-visual priming experiments investigates the role of bound stem allomorphs in the representation and processing of Finnish case inflected nouns. Niemi et al. (1994) and Laine et al. (1994) argue that Finnish nouns are parsed into stem and affix in reception and that the bound stem allomorphs have separate (visual) lexical representations. Recently J?rvikivi and Niemi (in press) have provided converging evidence for their claim based on a series of lexical decision experiments with Finnish stem allomorphs. The results from the present series of four follow-up experiments reported here showed that (isolated) bound stem allomorphs primed the recognition of the corresponding monomorphemic nouns significantly compared both to phonologically unrelated pseudowords and to phonologically minimally different pseudowords. Furthermore, not only did both phonologically transparent and opaque case inflected nouns prime the corresponding nominative singulars, but also there was no difference in priming between the two. The results are well in accordance and corroborate the hypotheses drawn from the earlier investigations. Moreover, they further indicate that bound stem allomorphs have representations on a purely formal level only, i.e., they serve as indices of and entering points to morphological/morphosyntactic information.     

Infants' visual anticipation of object structure in grasp planning

The coordination between visual and manual domains is a cornerstone of learning in early development. If infants anticipate an object's physical characteristics prior to contact (i.e., from visual inspection), they could learn more about the physical world through visual observation only than if manual exploration is required. In this experiment, infants grasped a series of four round balls quite similar in size and overall shape, but different in structure. Two were composed of solid hard plastic (one transparent, one opaque) in a rigid structure, and two were composed of more flexible plastic in a nonrigid structure. This nonrigid structure afforded grasping using a precision grasp with fingertips extending inside the ball's outer edge. In contrast, the rigid balls could be grasped only by a full-hand power grasp (due to the relative sizes of ball and infants' hands). The infants' manual anticipations were assessed in their first reach for each ball, prior to their first contact with the ball. In addition, grasping and other exploratory behaviors were assessed after contact with the ball. Results from this study suggest that infants from 5 to 15 months of age incorporate visible information about an object's structure into their action on the object. This provides evidence that visuomotor connections are present as soon as infants start reaching for objects, allowing them to select the appropriate grasp for an object's structure, even if they are not always capable of executing a pickup of the object using this grasp. Further research should investigate the discrepancies between infants' grasp planning and their grasp execution.     

Can blindness to response-compatible stimuli be observed in the absence of a response?

Blindness to response-compatible stimuli is the finding that targets are identified less accurately when presented during the planning or execution of a congruent response (e.g., right arrow presented during a right keypress) versus an incongruent response (e.g., right arrow presented during a left keypress). Accounts of this effect suggest the planning and execution of a response are critical to its observation. Five experiments investigated whether a blindness effect would be observed in the absence of a planned response. Results suggest that a planned response is not necessary to observe a content-specific blindness effect and that the blindness effect may actually comprise both an action-related component and a symbolic component that is distinct from the action-planning system.     

Effects of canonical color,luminance, and orientation on sustained inattentional blindness for scenes

Whether scene gist perception occurs automatically and unconsciously has been the subject of much debate. In addition to demonstrating a new method that adapts the Mack and Rock (1998) inattentional blindness cross procedure to allow for sustained inattentional blindness over a large number of trials, we report evidence from a series of experiments that shows that canonical scene features reduce inattentional blindness to scenes by facilitating the extraction of scene gist. When attentional demands are high, the combination of canonical color, canonical luminance, and canonical orientation reduces rates of inattentional blindness. However, when attentional demands are reduced, canonical features are independently sufficient to facilitate gist extraction and to capture attention. These results demonstrate that canonical color, canonical luminance, and canonical orientation all contribute to scene gist perception, and that when attentional demands are high, only highly canonical stimuli are sufficient to capture attention.     

Prospective and retrospective effects in human motor control: planning grasps for object rotation and translation

People pick up objects in ways that reflect prospective as well as retrospective control. Prospective control is indicated by planning for end-state comfort such that people grasp a cylinder to be rotated or translated with a hand orientation or at a height that affords a comfortable final posture. Retrospective control is indicated when people reuse a remembered grasp rather than using a new grasp that would ensure end-state comfort. Here, we asked whether these manifestations of prospective and retrospective control co-occur. We did so by having healthy young-adult participants grasp a cylinder to rotate and translate it between a horizontal position and a vertical position at each of five heights. We found that participants planned for comfortable final hand orientations for first moves but relied on recall for subsequent hand orientations. The results suggest that motor planning is sensitive to computational as well as physical demands and that object rotation and translation are not dissociable features of motor control, at least as reflected in their contributions to grasp selection. The latter result is consistent with the hypothesis that movements constitute holistic body changes between successive goal postures.     

The time to name disoriented natural objects

A series of experiments revealed systematic effects of orientation on the time required to identify line drawings of natural objects. Naming time increases as patterns are rotated further from the upright. With practice, however, the effect of orientation is reduced considerably. Furthermore, the reduced orientation effect with practice on a set of objects does not transfer to a new set of objects, suggesting that the acquired ability to reduce the orientation effect is specific to particular patterns. Finally, for departures in orientation from the upright between 0° and 120°, the magnitude of the orientation effect on identification for patterns seen for the first time is equivalent to that found in a mental rotation task using the same patterns (making left/right decisions about rotated patterns). This final result suggests that novel depictions of a known class of objects may be identified by a process of mental rotation.     

The scene and the unseen: Manipulating photographs for experiments on change blindness and scene memory

The change blindness paradigm, in which participants often fail to notice substantial changes in a scene, is a popular tool for studying scene perception, visual memory, and the link between awareness and attention. Some of the most striking and popular examples of change blindness have been demonstrated with digital photographs of natural scenes; in most studies, however, much simpler displays, such as abstract stimuli or “free-floating” objects, are typically used. Although simple displays have undeniable advantages, natural scenes remain a very useful and attractive stimulus for change blindness research. To assist researchers interested in using natural-scene stimuli in change blindness experiments, we provide here a step-by-step tutorial on how to produce changes in natural-scene images with a freely available image-processing tool (GIMP). We explain how changes in a scene can be made by deleting objects or relocating them within the scene or by changing the color of an object, in just a few simple steps. We also explain how the physical properties of such changes can be analyzed using GIMP and MATLAB (a high-level scientific programming tool). Finally, we present an experiment confirming that scenes manipulated according to our guidelines are effective in inducing change blindness and demonstrating the relationship between change blindness and the physical properties of the change and inter-individual differences in performance measures. We expect that this tutorial will be useful for researchers interested in studying the mechanisms of change blindness, attention, or visual memory using natural scenes.