Active vision in passive locomotion: real‐world free viewing in infants and adults

Visual exploration in infants and adults has been studied using two very different paradigms: free viewing of flat screen displays in desk‐mounted eye‐tracking studies and real‐world visual guidance of action in head‐mounted eye‐tracking studies. To test whether classic findings from screen‐based studies generalize to real‐world visual exploration and to compare natural visual exploration in infants and adults, we tested observers in a new paradigm that combines critical aspects of both previous techniques: free viewing during real‐world visual exploration. Mothers and their 9‐month‐old infants wore head‐mounted eye trackers while mothers carried their infants in a forward‐facing infant carrier through a series of indoor hallways. Demands for visual guidance of action were minimal in mothers and absent for infants, so both engaged in free viewing while moving through the environment. Similar to screen‐based studies, during free viewing in the real world low‐level saliency was related to gaze direction. In contrast to screen‐based studies, only infants – not adults – were biased to look at people, participants of both ages did not show a classic center bias, and mothers and infants did not display high levels of inter‐observer consistency. Results indicate that several aspects of visual exploration of a flat screen display do not generalize to visual exploration in the real world.     

Perceptual grouping does not affect multi-attribute decision making if no processing costs are involved

Adaptive strategy selection implies that a decision strategy is chosen based on its fit to the task and situation. However, other aspects, such as the way information is presented, can determine information search behavior; especially when the application of certain strategies over others is facilitated. But are such display effects on multi-attribute decisions also at work when the manipulation does not entail differential costs for different decision strategies? Three Mouselab experiments with hidden information and one eye tracking experiment with an open information board revealed that decision behavior is unaffected by purely perceptual manipulations of the display based on Gestalt principles; that is, based on manipulations that induce no noteworthy processing costs for different information search patterns. We discuss our results in the context of previous findings on display effects; specifically, how the combination of these findings and our results reveal the crucial role of differential processing costs for different strategies for the emergence of display effects. This finding describes a boundary condition of the commonly acknowledged influence of information displays and is in line with the ideas of adaptive strategy selection and cost–benefit tradeoffs.     

Conditional control in visual selection

Attention and eye movements provide a window into the selective processing of visual information. Evidence suggests that selection is influenced by various factors and is not always under the strategic control of the observer. The aims of this tutorial review are to give a brief introduction to eye movements and attention and to outline the conditions that help determine control. Evidence suggests that the ability to establish control depends on the complexity of the display as well as the point in time at which selection occurs. Stimulus-driven selection is more probable in simple displays than in complex natural scenes, but it critically depends on the timing of the response: Salience determines selection only when responses are triggered quickly following display presentation, and plays no role in longer-latency responses. The time course of selection is also important for the relationship between attention and eye movements. Specifically, attention and eye movements appear to act independently when oculomotor selection is quick, whereas attentional processes are able to influence oculomotor control when saccades are triggered only later in time. This relationship may also be modulated by whether the eye movement is controlled in a voluntary or an involuntary manner. To conclude, we present evidence that shows that visual control is limited in flexibility and that the mechanisms of selection are constrained by context and time. The outcome of visual selection changes with the situational context, and knowing the constraints of control is necessary to understanding when and how visual selection is truly controlled by the observer.     

Active and passive scene recognition across views.

Recent evidence suggests that scene recognition across views is impaired when an array of objects rotates relative to a stationary observer, but not when the observer moves relative to a stationary display [Simons, D.J., Wang, R.F., 1998. Perceiving real-world viewpoint changes. Psychological Science 9, 315-320]. The experiments in this report examine whether the relatively poorer performance by stationary observers across view changes results from a lack of perceptual information for the rotation or from the lack of active control of the perspective change, both of which are present for viewpoint changes. Three experiments compared performance when observers passively experienced the view change and when they actively caused the change. Even with visual information and active control over the display rotation, change detection performance was still worse for orientation changes than for viewpoint changes. These findings suggest that observers can update a viewer-centered representation of a scene when they move to a different viewing position, but such updating does not occur during display rotations even with visual and motor information for the magnitude of the change. This experimental approach, using arrays of real objects rather than computer displays of isolated individual objects, can shed light on mechanisms that allow accurate recognition despite changes in the observer's position and orientation.     

Aesthetic issues in spatial composition: effects of vertical position and perspective on framing single objects

Aesthetic preference for the vertical composition of single-object pictures was studied through a series of two-alternative forced-choice experiments. The results reveal the influence of several factors, including spatial asymmetries in the functional properties of the object and the typical position of the object relative to the observer. With asymmetric side views of objects, people generally prefer objects typically located below the observer's viewpoint (e.g., a bowl or swimming stingray) to be below the center of the frame and objects typically located above the observer's viewpoint (e.g., a light fixture or flying eagle) to be above the center of the frame. In addition, people generally prefer symmetric views of those same objects from directly above or directly below to be closer to the center of the frame. We suggest that these results can be unified by the hypothesis that people prefer the object's "affordance space" to be centered within the frame.     

Contextual cueing in multiple object tracking

In this study, we examined whether visual context can be learned through a dynamic display and whether it can facilitate sustained attentional tracking by combining a multiple object tracking (MOT) task and a contextual cueing procedure. The trajectories of the targets and distractors in the MOT task were made invariant by repeatedly presenting them. The results revealed that when the targets were repeatedly displayed, tracking performance implicitly improved, and this effect was enhanced when the unattended distractors in the displays were also repeated. However, the repetition of the distractors alone did not produce any effect. Interestingly, when the targets and distractors were switched in a display in which the distractors had been previously repeated, the tracking performance was impaired as compared with that in the case of nonrepeated displays. We concluded that the contextual information in a dynamic display facilitates attentional tracking and that different types of contextual modulations occurred in MOT processes, such as facilitation for attended targets and inhibition for ignored distractors.     

Speed, size, and edge-rate information for the detection of collision events

In the present study an alternative analysis to tau was considered that was based on perceived speed and size and that assumed constant deceleration for the detection of collision events. Observers were presented with displays simulating a 3-D environment with obstacles in the path of observer motion. During the trial, observer motion decelerated at a constant rate and was followed by a blackout prior to the end of the display. Observers had to detect which trials resulted in a collision. The results indicate that collision detection varied as a function of the size of the obstacles, observer speed, and edge rate--findings not predicted by an analysis of tau. The results suggest that observers use an analysis based on speed and size information. A model that assumes constant deceleration is proposed for braking control.     

Development of sensitivity to information for impending collision

Infants were tested in three experiments to study the development of sensitivity to information for impending collision and to investigate the hypothesis that postural changes of very young infants in response to an approaching object are of a tracking rather than of a defensive nature. Experiment 1 involved the presentation of three types of shadow projection displays, specifying (1) collision, (2) noncollision, and (3) a nonexpanding rising contour, to infants from 1 to 9 months of age. Avoidance of collision appears to be absent in 1- to 2-month-olds, begins to develop in 4- to 6-month-olds, and is present in 8- to 9-month-old infants. In Experiment 2, 1- to 2-month-old infants were presented with optical expansion patterns which specified collision and noncollision. The top contour of these displays stayed at eye level. No significant difference was observed between reaction to the collision and the noncollision displays, suggesting that the young infants were tracking the displays and not attempting to avoid collision. Experiment 3 was designed to determine whether an approaching real object might elicit an avoidance response in infants not sensitive to an optical display specifying collision. No evidence of avoidance behavior was observed in the 1- to 2-month-olds; however, avoidance, as indexed by blinking, does appear to be present at 4 months of age.     

儿童对观察者预期造成的模糊刺激解释多样性的理解

研究考察6~8岁儿童在由观察者预期造成的对模糊信息有多样解释上的理解.操纵影响观察者预期的因素,包括知觉经验、知识水平、先前经历和偏见,要求儿童预测观察者对局限视野图形或两可动作信息的解释.结果表明,6岁儿童仅对观察者偏见影响其对行动者行为的解释拥有部分理解,他们还不能理解知觉经验和知识水平会影响观察者对视觉刺激的解释,以及先前经历会影响观察者对行动者行为的解释.7岁儿童除了知识水平外,其它三方面的理解都已发展起来.8岁儿童可以理解多种观察者预期造成的解释差异,解释性心理理论比较稳定,但离完全成熟的理解还有一段距离.     

Witnessed aggression: influence of an observer's sex and values on aggressive responding.

Two experiments investigated the effects of the presence of an observer on aggressive responding. In one experiment, male subjects observed by a male aggressed more than those observed by a female. When the male observer was removed from the situation, subjects' level of aggressiveness more closely matched the level manifested by the opponent. The removal of the female observer had little effect on the subjects' behavior. In the second experiment, the male or female observer of the subject's behavior was disguised as a member of an organization with explicit values (aggressive or pacifistic) regarding the use of aggression. In this case, significant differences in aggression were associated with the observer's values but not the observer's sex. Following the departure of the observer, the shock settings of subjects in the two aggressive-value observer groups showed a signifcant decrease. The average shock setting of subjects in the two pacifistic-value observer groups remained at about the same level. In sum, the results indicated that the subjects' aggressive behavior was apparently a function of their expectations of approval for such behavior, based on the inferred or explicit values of the observer. The results were further discussed in terms of social learning theory.     

The observer-relative velocity field as the basis for effective motion parallax

Earlier studies of motion parallax found unambiguous relative depth perception when random dot patterns were systematically translated in accordance with either motion of the observer's head or motion of the display scope. The need for such relative motion between an observer and a flow field was examined by placing a flow field in a limited area (window) in a large scope and translating the window relative to the observer. Accuracy in judging surface orientation and quantitative depth estimates were determined by the velocity field relative to the observer and were not measurably affected by whether this field was produced with a stationary or a moving window. Accuracy was consistently higher for smaller ratios of maximum to minimum projected velocities, reaching 100% in one experiment with a 1.12:1 ratio. We conclude that fully effective motion parallax does not require relative motion between the observer's head and the contours of a flow field.     

Age-related differences in collision detection during deceleration

Observers were presented with displays simulating a 3-D environment with obstacles in the path of motion. During the trial, observer motion decelerated at a constant rate and was followed by a blackout prior to the end of the display. On some trials the rate of deceleration resulted in stopping before the collision, whereas on other trials the rate of deceleration resulted in a collision with the obstacles. The observer's task was to detect which trials simulated an impending collision. Proportion of collision judgments was greater for older as compared with younger observers when a collision was not simulated. Older observers showed less sensitivity to detect collisions than younger observers did, particularly at high speeds. The age-dependent results are discussed in terms of analyses based on tau and constant deceleration. The results suggest that increased accident rates for older drivers may be due to an inability to detect collisions at high speeds.     

Target objects defined by a conjunction of colour and shape can be selected independently and in parallel

It is generally assumed that during search for targets defined by a feature conjunction, attention is allocated sequentially to individual objects. We tested this hypothesis by tracking the time course of attentional processing biases with the N2pc component in tasks where observers searched for two targets defined by a colour/shape conjunction. In Experiment 1, two displays presented in rapid succession (100 ms or 10 ms SOA) each contained a target and a colour-matching or shape-matching distractor on opposite sides. Target objects in both displays elicited N2pc components of similar size that overlapped in time when the SOA was 10 ms, suggesting that attention was allocated in parallel to both targets. Analogous results were found in Experiment 2, where targets and partially matching distractors were both accompanied by an object without target-matching features. Colour-matching and shape-matching distractors also elicited N2pc components, and the target N2pc was initially identical to the sum of the two distractor N2pcs, suggesting that the initial phase of attentional object selection was guided independently by feature templates for target colour and shape. Beyond 230 ms after display onset, the target N2pc became superadditive, indicating that attentional selection processes now started to be sensitive to the presence of feature conjunctions. Results show that independent attentional selection processes can be activated in parallel by two target objects in situations where these objects are defined by a feature conjunction.     

Perceiving curvilinear heading in the presence of moving objects

Four experiments were directed at understanding the influence of multiple moving objects on curvilinear (i.e., circular and elliptical) heading perception. Displays simulated observer movement over a ground plane in the presence of moving objects depicted as transparent, opaque, or black cubes. Objects either moved parallel to or intersected the observer's path and either retreated from or approached the moving observer. Heading judgments were accurate and consistent across all conditions. The significance of these results for computational models of heading perception and for information in the global optic flow field about observer and object motion is discussed.     

What Am I Looking at? Interpreting Dynamic and Static Gaze Displays

Displays of eye movements may convey information about cognitive processes but require interpretation. We investigated whether participants were able to interpret displays of their own or others' eye movements. In Experiments 1 and 2, participants observed an image under three different viewing instructions. Then they were shown static or dynamic gaze displays and had to judge whether it was their own or someone else's eye movements and what instruction was reflected. Participants were capable of recognizing the instruction reflected in their own and someone else's gaze display. Instruction recognition was better for dynamic displays, and only this condition yielded above chance performance in recognizing the display as one's own or another person's (Experiments 1 and 2). Experiment 3 revealed that order information in the gaze displays facilitated instruction recognition when transitions between fixated regions distinguish one viewing instruction from another. Implications of these findings are discussed.     

Mental imagery and the third dimension

What sort of medium underlies imagery for three-dimensional scenes? In the present investigation, the time subjects took to scan between objects in a mental image was used to infer the sorts of geometric information that images preserve. Subjects studied an open box in which five objects were suspended, and learned to imagine this display with their eyes closed. In the first experiment, subjects scanned by tracking an imaginary point moving in a straight line between the imagined objects. Scanning times increased linearly with increasing distance between objects in three dimensions. Therefore metric 3-D information must be preserved in images, and images cannot simply be 2-D "snapshots." In a second experiment, subjects scanned across the image by "sighting" objects through an imaginary rifle sight. Here scanning times were found to increase linearly with the two-dimensional separations between objects as they appeared from the original viewing angle. Therefore metric 2-D distance information in the original perspective view must be preserved in images, and images cannot simply be 3-D "scale-models" that are assessed from any and all directions at once. In a third experiment, subjects mentally rotated the display 90 degrees and scanned between objects as they appeared in this new perspective view by tracking an imaginary rifle signt, as before. Scanning times increased linearly with the two-dimensional separations between objects as they would appear from the new relative viewing perspective. Therefore images can display metric 2-D distance information in a perspective view never actually experiences, so mental images cannot simply be "snapshot plus scale model" pairs. These results can be explained by a model in which the three-dimensional structure of objects is encoded in long-term memory in 3-D object-centered coordinate systems. When these objects are imagined, this information is then mapped onto a single 2-D "surface display" in which the perspective properties specific to a given viewing angle can be depicted. In a set of perceptual control experiments, subjects scanned a visible display by (a) simply moving their eyes from one object to another, (b) sweeping an imaginary rifle sight over the display, or (c) tracking an imaginary point moving from one object to another. Eye-movement times varied linearly with 2-D interobject distance, as did time to scan with an imaginary rifle sight; time to tract a point varied independently with the 3-D and 2-D interobject distances. These results are compared with the analogous image scanning results to argue that imagery and perception share some representational structures but that mental image scanning is a process distinct from eye movements or eye-movement commands.     

Induced self-motion in central vision

Previous research on visually induced self-motion found that stimulation of the central visual field (up to 30 degrees in diameter) results in perceived object motion while self-motion requires peripheral stimulation. In the present study, perceived self-motion was induced with a radially expanding pattern simulating observer motion through a space filled with dots, with visual angles of 7.5 degrees, 10.6 degrees, 15 degrees, and 21.2 degrees. Speed and texture density were also varied. The duration of reported self-motion (a) decreased with increased speed, (b) failed to increase with increased visual angle, and (c) decreased with visual angle at the highest speed level. In a second experiment, subjects rated the perceived depth of the displays. The speed and speed/area interaction effects on judged depth matched those found for induced self-motion. These results suggest an extension of the focal/ambient theory: In addition to a more primitive ambient processing mode that requires peripheral vision, there is a higher level system concerned with ambient processing that functions in the central visual field and uses more complex stimulus information, such as internal depth represented in a radially expanding pattern.     

Eye movements across viewpoint changes in multiple object tracking

Observers can visually track multiple objects that move independently even if the scene containing the moving objects is rotated in a smooth way. Abrupt scene rotations yield tracking more difficult but not impossible. For nonrotated, stable dynamic displays, the strategy of looking at the targets' centroid has been shown to be of importance for visual tracking. But which factors determine successful visual tracking in a nonstable dynamic display? We report two eye tracking experiments that present evidence for centroid looking. Across abrupt viewpoint changes, gaze on the centroid is more stable than gaze on targets indicating a process of realigning targets as a group. Further, we show that the relative importance of centroid looking increases with object speed.     

Choosing and using geospatial displays: effects of design on performance and metacognition

Interactive display systems give users flexibility to tailor their visual displays to different tasks and situations. However, in order for such flexibility to be beneficial, users need to understand how to tailor displays to different tasks (to possess "metarepresentational competence"). Recent research suggests that people may desire more complex and realistic displays than are most effective (Smallman & St. John, 2005). In Experiment 1, undergraduate students were tested on a comprehension task with geospatial displays (weather maps) that varied in the number of extraneous variables displayed. Their metacognitive judgments about the relative effectiveness of the displays were also solicited. Extraneous variables slowed response time and increased errors, but participants favored complex maps that looked more realistic about one third of the time. In Experiment 2, the eye fixations of undergraduate students were monitored as they performed the comprehension task. Complex maps that looked more realistic led to more eye fixations on both task-relevant and task-irrelevant regions of the displays. Experiment 3 compared performance of experienced meteorologists and undergraduate students on the comprehension and metacognitive tasks. Meteorologists were as likely as undergraduate students to prefer geographically complex (realistic) displays and more likely than undergraduates to opt for displays that added extraneous weather variables. However, meteorologists were also slower and less accurate with complex than with simple displays. This work highlights the importance of empirically testing principles of visual display design and suggests some limits to metarepresentational competence.     

前瞻记忆需要经过策略加工:来自眼动的证据

基于视觉搜索范式,采用多目标刺激呈现的眼动测量方法探索事件性前瞻记忆的加工过程。行为结果显示,对靶目标以及干扰目标的击中率比前瞻记忆目标的击中率均更高,只有前瞻线索和干扰目标比只有靶目标的反应时更长。眼动结果显示,第一注视时间和总注视时间从干扰目标、靶目标到前瞻目标逐渐增长,在前瞻漏报中存在注视到前瞻线索的可能性,搜索序列中靶目标的存在会干扰对前瞻线索的注意。行为和眼动的结果表明,前瞻线索是否被注视到并不会决定前瞻记忆是否会成功,对于意向的实现需要目标检查或者预备注意加工过程,支持策略控制理论。