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.     

Reconciling change blindness with long-term memory for objects

How can we reconcile remarkably precise long-term memory for thousands of images with failures to detect changes to similar images? We explored whether people can use detailed, long-term memory to improve change detection performance. Subjects studied a set of images of objects and then performed recognition and change detection tasks with those images. Recognition memory performance exceeded change detection performance, even when a single familiar object in the postchange display consistently indicated the change location. In fact, participants were no better when a familiar object predicted the change location than when the displays consisted of unfamiliar objects. When given an explicit strategy to search for a familiar object as a way to improve performance on the change detection task, they performed no better than in a 6-alternative recognition memory task. Subjects only benefited from the presence of familiar objects in the change detection task when they had more time to view the prechange array before it switched. Once the cost to using the change detection information decreased, subjects made use of it in conjunction with memory to boost performance on the familiar-item change detection task. This suggests that even useful information will go unused if it is sufficiently difficult to extract.     

Does the body image exist in three dimensions? The study of visual mental representation of a body and a nonbody object

Do the mental images of 3-dimensional objects recreate the depth characteristics of the original objects? This investigation of the characteristics of mental images utilized a novel boundary-detection task that required participants to relate a pair of crosses to the boundary of an image mentally projected onto a computer screen. 48 female participants with body attitudes within expected normal range were asked to image their own body and a familiar object from the front and the side. When the visual mental image was derived purely from long-term memory, accuracy was better than chance for the front (64%) and side (63%) of the body and also for the front (55%) and side (68%) of the familiar nonbody object. This suggests that mental images containing depth and spatial information may be generated from information held in long-term memory. Pictorial exposure to views of the front or side of the objects was used to investigate the representations from which this 3-dimensional shape and size information is derived. The results are discussed in terms of three possible representational formats and argue that a front-view 2 1/2-dimensional representation mediates the transfer of information from long-term memory when depth information about the body is required.     

Facilitated pointing to remembered objects in front: Evidence for egocentric retrieval or for spatial priming?

Recent spatial memory theories propose that long-term spatial memories are retrieved egocentrically. One source of evidence comes from imagined perspective taking, in which participants learn an object layout, later imagine standing at one object and facing a second (orienting) object, and then point to a third (target) object from the imagined perspective. Pointing is faster for target objects in the anterior than in the posterior half of imaginal space. This “front facilitation” is consistent with asymmetric sensory and biomechanical body properties (favoring the anterior half of body space), supporting claims of egocentric retrieval. However, front facilitation might actually result from spatial priming: Proximity differences might cause orienting objects to prime target objects more in the anterior than in the posterior half of imagined space. Using a modified perspectivetaking task that unconfounded front facilitation and spatial priming, two experiments identified separate influences of front facilitation and spatial priming when participants imagined perspectives within the surrounding environment or a remote environment.     

Event-related potential (ERP) indices of infants' recognition of familiar and unfamiliar objects in two and three dimensions

We measured infants' recognition of familiar and unfamiliar 3-D objects and their 2-D representations using event-related potentials (ERPs). Infants differentiated familiar from unfamiliar objects when viewing them in both two and three dimensions. However, differentiation between the familiar and novel objects occurred more quickly when infants viewed the object in 3-D than when they viewed 2-D representations. The results are discussed with respect to infants' recognition abilities and their understanding of real objects and representations. This is the first study using 3-D objects in conjunction with ERPs in infants, and it introduces an interesting new methodology for assessing infants' electrophysiological responses to real objects.     

Motor imagery in typing: effects of typing style and action familiarity

The influences of typing style and action familiarity on executed and imagined typing were investigated. A group of touch typists and a group of hunt-and-peck typists were asked to imagine and execute typing texts of different lengths in two different styles: with ten fingers (familiar for touch typists, unfamiliar for hunt-and-peck typists) and with two fingers (unfamiliar for touch typists, familiar for hunt-and-peck typists). The imagination (but not the execution) of familiar and unfamiliar typing was correlated in both groups, indicating that participants used skill knowledge from the familiar action to imagine the unfamiliar action. Only when touch typists imagined familiar typing accurate motor imagery was observed (similar durations of and positive correlations between imagination and execution). When touch typists imagined unfamiliar typing, the average imagination durations resembled the execution durations, but correlations indicated individual differences in the processes of imagination and execution. Hunt-and-peck typists showed shorter imagination than execution durations with both familiar and unfamiliar typing, indicating that in both styles they did not imagine all details of typing. Also, they did not imagine some details specifically related to unfamiliar typing (reflected in particularly high percentages of absolute error). However, correlations indicated that individual difficulties in executing the unfamiliar action were reflected in the imagination durations. In conclusion, skill knowledge from familiar actions is used to imagine unfamiliar actions. Familiarity with actions promotes accurate motor imagery, but only if stable internal action representations have been acquired, and not if action control relies on online, step-by-step control. However, stable internal action representations of familiar actions may be detrimental for imagery of unfamiliar actions.     

Quantifying the role of context in visual object recognition

An object's context may serve as a source of information for recognition when the object's image is degraded. The current study aimed to quantify this source of information. Stimuli were photographs of objects divided into quantized blocks. Participants decreased block size (increasing resolution) until identification. Critical resolution was compared across three conditions: (1) when the picture of the target object was shown in isolation, (2) in the object's contextual setting where that context was unfamiliar to the participant, and (3) where that context was familiar to the participant. A second experiment assessed the role of object familiarity without context. Results showed a profound effect of context: Participants identified objects in familiar contexts with minimal resolution. Unfamiliar contexts required higher-resolution images, but much less so than those without context. Experiment 2 found a much smaller effect of familiarity without context, suggesting that recognition in familiar contexts is primarily based on object-location memory.     

The permanence of mental objects: testing magical thinking on perceived and imaginary realities

This study tested participants' preparedness to acknowledge that an object could change as a result of magical intervention. Six- and 9-year-old children and adults treated perceived and imagined objects as being equally permanent. Adults treated a fantastic object as significantly less permanent than either perceived or imagined objects. Results were similar when a different type of mental-physical causality--a participant's own wish--was examined. Adults were also tested on the permanence of personally significant imagined objects (participants' images of their future lives). Although almost all participants claimed that they did not believe in magic, in test trials they were not prepared to rule out the possibility that their future lives could be affected by a magical curse.     

Relative distance judgments of familiar and unfamiliar objects viewed under representatively natural conditions

Carlson and Tassone (1971) reported that an object of familiar size viewed at an appreciable distance is perceived to be more distant than an unfamiliar object. Six experiments were designed to examine this effect. The results indicated that the effect is not dependent on Carlson and Tassone's method for assessing perceived relative distance; it occurs at some minimum viewing distance; it is unlikely to be caused by stimulus attributes confounded with the familiar versus unfamiliar size dichotomy; appears to be specific to judgments of the familiar object itself; and it does not occur if the familiar and unfamiliar objects have a common reference target. These findings are discussed with respect to the issue of whether familiar size influences perceived distance as distinct from influencing judgments of distance.     

Object segmentation by top-down processes

In cluttered scenes, some object boundaries may not be marked by image cues. In such cases, the boundaries must be defined top-down as a result of object recognition. Here we ask if observers can retain the boundaries of several recognized objects in order to segment an unfamiliar object. We generated scenes consisting of neatly stacked objects, and the objects themselves consisted of neatly stacked coloured blocks. Because the blocks were stacked the same way within and across objects, there were no visual cues indicating which blocks belonged to which objects. Observers were trained to recognize several objects and we tested whether they could segment a novel object when it was surrounded by these familiar, studied objects. The observer's task was to count the number of blocks comprising the target object. We found that observers were able to accurately count the target blocks when the target was surrounded by up to four familiar objects. These results indicate that observers can use the boundaries of recognized objects in order to accurately segment, top-down, a novel object.     

Updating displays after imagined object and viewer rotations

Six experiments compared spatial updating of an array after imagined rotations of the array versus viewer. Participants responded faster and made fewer errors in viewer tasks than in array tasks while positioned outside (Experiment 1) or inside (Experiment 2) the array. An apparent array advantage for updating objects rather than locations was attributable to participants imagining translations of single objects rather than rotations of the array (Experiment 3). Superior viewer performance persisted when the array was reduced to 1 object (Experiment 4); however, an object with a familiar configuration improved object performance somewhat (Experiment 5). Object performance reached near-viewer levels when rotations included haptic information for the turning object. The researchers discuss these findings in terms of the relative differences in which the human cognitive system transforms the spatial reference frames corresponding to each imagined rotation.     

Powered by Imagination: Nanobots at the Science Photo Library

Nanobots have been a key image deployed in nanoscience and nanofiction. At present nanobots are still largely ‘imaginary’. But what do ‘imaginary’ nanobots look like, how are they visually and imaginatively constructed and what functions are they envisioned to have? And what can such images tell us about the aesthetic and cultural conventions and metaphors that are employed, and expectations and visions created or engineered, in the process of ‘visualizing’ nanoscience and nanotechnology for science and society? To answer these questions images of nanobots available at the Science Photo Library were studied. Nanobots were envisioned as ‘working’ mostly in futuristic domains of health and medicine. Most nanobots were artistically rendered as familiar objects or animals, as fulfilling useful functions in healthcare, rather than as running wild and causing harm. Such images were displayed mostly to engage lay publics with biotechnology and nanotechnology. By selectively using metaphors, images of nanobots tended to assimilate the unknown into the known and the unfamiliar into the familiar. This assimilation invites viewers to react to these images as if nanobots already existed and as if they were normal. Thus the images open up a space for ‘normalizing’ this new, rather speculative technology; it is framed in such a way as to invite public acceptance and even excitement.     

If you say thee uh you are describing something hard: the on-line attribution of disfluency during reference comprehension

Eye-tracking and gating experiments examined reference comprehension with fluent (Click on the red. . .) and disfluent (Click on [pause] thee uh red . . .) instructions while listeners viewed displays with 2 familiar (e.g., ice cream cones) and 2 unfamiliar objects (e.g., squiggly shapes). Disfluent instructions made unfamiliar objects more expected, which influenced listeners' on-line hypotheses from the onset of the color word. The unfamiliarity bias was sharply reduced by instructions that the speaker had object agnosia, and thus difficulty naming familiar objects (Experiment 2), but was not affected by intermittent sources of speaker distraction (beeps and construction noises; Experiments 3). The authors conclude that listeners can make situation-specific inferences about likely sources of disfluency, but there are some limitations to these attributions.     

Repetition priming and the haptic recognition of familiar and unfamiliar objects

In four experiments, we examined the haptic recognition of 3-D objects. In Experiment 1, blindfolded participants named everyday objects presented haptically in two blocks. There was significant priming of naming, but no cost of an object changing orientation between blocks. However, typical orientations of objects were recognized more quickly than nonstandard orientations. In Experiment 2, participants accurately performed an unannounced test of memory for orientation. The lack of orientation-specific priming in Experiment 1, therefore, was not because participants could not remember the orientation at which they had first felt an object. In Experiment 3, we examined haptic naming of objects that were primed either haptically or visually. Haptic priming was greater than visual priming, although significant cross-modal priming was also observed. In Experiment 4, we tested recognition memory for familiar and unfamiliar objects using an old-new recognition task. Objects were recognized best when they were presented in the same orientation in both blocks, suggesting that haptic object recognition is orientation sensitive. Photographs of the unfamiliar objects may be downloaded from www.psychonomic.org/archive.     

Color-object interference in young children: A Stroop effect in children 3½-6½ years old

The Stroop color–word task cannot be administered to children who are unable to read. However, our color–object Stroop task can. One hundred and sixty-eight children of 3½–6½ years (50% female; 24 children at each 6-month interval) were shown line drawings of familiar objects in a color that was congruent (e.g., an orange carrot), incongruent (e.g., a green carrot), or neutral (for objects having no canonical color [e.g., a red book]), and abstract shapes, each drawn in one of six colors. Half the children were asked to name the color in which each object was drawn, and half were to name each object. Children's predominant tendency was to say what the object was; when instructed to do otherwise they were slower and less accurate. Children were faster and more accurate at naming the color of a stimulus when the form could not be named (abstract shape) than when it could, even if in its canonical color. The heightened interference to color-naming versus object-naming was not due to lack of familiarity with color names or group differences: Children in the color condition were as fast and accurate at naming the colors of abstract shapes as were children in the form condition at naming familiar objects.     

Emergent two-dimensional patterns in images rotated in depth

Once a person has observed a three-dimensional scene, how accurately can he or she then imagine the appearance of that scene from different viewing angles? In a series of experiments addressed to this question, subjects formed mental images of a set of objects hanging in a clear cylinder and mentally rotated their images as they physically rotated the cylinder by various amounts. They were asked to perform four tasks, each demanding the ability to "see" the two-dimensional patterns that should emerge in their images if the images depicted the new perspective view accurately--(a) Subjects described the two-dimensional geometric shape that the imagined objects formed in an image rotated 90 degrees; (b) they "scanned" horizontally from one imagined object to another in a rotated image; (c) they physically rotated the empty cylinder together with their image until two of the imagined objects were vertically aligned; and (d) they adjusted a marker to line up with a single object in a rotated image. The experimental results converged to suggest that subjects' images accurately displayed the two-dimensional patterns emerging from a rotation in depth. However, the amount by which they rotated their image differed systematically from the amount specified by the experimenter. Results are discussed in the context of a model of the mental representation of physical space that incorporates two types of structures, one representing the three-dimensional layout of a scene, and the other representing the two-dimensional perspective view of the scene from a given vantage point.     

Artifacts and natural kinds: children's judgments about whether objects are owned

People's behavior in relation to objects depends on whether they are owned. But how do people judge whether objects are owned? We propose that people expect human-made objects (artifacts) to be more likely to be owned than naturally occurring objects (natural kinds), and we examine the development of these expectations in young children. Experiment 1 found that when shown pictures of familiar kinds of objects, 3-year-olds expected artifacts to be owned and inanimate natural kinds to be non-owned. In Experiments 2A and 2B, 3-6-year-olds likewise had different expectations about the ownership of unfamiliar artifacts and natural kinds. Children at all ages viewed unfamiliar natural kinds as non-owned, but children younger than 6 years of age only endorsed artifacts as owned at chance rates. In Experiment 3, children saw the same pictures but were also told whether objects were human-made. With this information provided, even 3-year-olds viewed unfamiliar artifacts as owned. Finally, in Experiment 4, 4- and 5-year-olds chose unfamiliar artifacts over natural kinds when judging which object in a pair belongs to a person, but not when judging which the person prefers. These experiments provide first evidence about how children judge whether objects are owned. In contrast to claims that children think about natural kinds as being similar to artifacts, the current findings reveal that children have differing expectations about whether they are owned.     

Difference between highlight and object colors enhances glossiness

The effect of highlight and object colors on perception of glossiness was examined. Ten participants rated glossiness of object images. The color coordinates of objects and highlights were varied while luminance of each pixel was unchanged. Four colors were used for objects and highlights. Objects were perceived as glossier when the highlight color was different from the object color than when they were the same. Objects with some unnatural combinations of highlight and object colors were perceived to be as glossy as those with natural color combinations. The results suggested that differences between highlight and object colors enhance perceived glossiness and that perceived glossiness does not depend on naturalness of color combination for highlights and objects.