Search

Perception of the physical environment and emotions relevant to the social environment are integrated into a resource-based account. Animals, unlike plants, must move around their environment to obtain resources and avoid predators, which in turn necessitates perception. Animate creatures also must coordinate perceptions of their internal and external environments to balance bodily expenditures of energy and environmental demands. Consequently, perceptions of distances and the steepness of hills increase with exhaustion and glucose depletion and decrease with physical fitness. They also increase with emotions of sadness and fear and decrease with the accessibility of social resources. Social support during times of stress even increases the available glucose in the blood. The extraordinary success of the human species is believed to have depended on their living in cooperative social groups. Hence, social inclusion is a valuable resource. We propose an emotion-as-information model in which emotions serve as information for managing resources, especially social ones.

Bodily boundaries are computed by integrating multisensory bodily signals and can be experimentally manipulated using bodily illusions. Research on tool use demonstrates that tools alter body representations motorically to account for changes in a user's action repertoire. The present experiment sought to unify perceptual and motoric accounts of tool embodiment using a modified Rubber Hand Illusion (RHI) that also addressed the skill and practice aspects of the tool use literature. In Experiment 1, synchronous multisensory stimulation induced perceptual embodiment of a tool, chopsticks. The embodiment of chopsticks was stronger for more skilled participants, and if the illusion was preceded by tool use. In Experiment 2, the illusion was not elicited with a different type of tool, a teacup, showing that not all objects can be incorporated. This experiment helps to clarify the role of perceptual and motoric embodiment and suggests future avenues for research into tools embodiment using this method.

Through experience, people learn that a given magnitude of walking produces an associated magnitude of optic flow. Artificially altering this relationship has both behavioral and perceptual consequences: walking on a treadmill results in zero translational optic flow and causes people to subsequently drift forward when attempting to walk in place while blindfolded (they have learned that forward walking is required to remain stationary). Similarly, after walking on a treadmill people perceive the walking distance to targets to be greater (they have recalibrated the magnitude of walking required to reach the target). While the measurement unit for walking magnitude in this relationship has been treated as walking speed (stride length * [steps / time]), recent experiments suggest that walkable distances may instead be measured in bioenergetic units (i.e., the magnitude of energy required to produce a given magnitude of optic flow). In the first experiment, zero translational optic flow was paired with a constant walking speed, and walking energy was manipulated by varying the incline of the treadmill. Participants who walked on an inclined treadmill drifted farther while attempting to walk in place than participants who walked on a flat treadmill. A follow-up experiment presented optic flow via an immersive virtual environment, and no difference between flat and inclined treadmill walking was found, thereby showing that the effect found in the first experiment was not an artifact of biomechanical differences associated with flat versus inclined treadmill walking. The results support the hypothesis that walking magnitude is scaled by bioenergetic units.

The embodiment of tools and rubber hands is believed to involve the modification of two separate body representations: the body schema and the body image, respectively. It is thought that tools extend the capabilities of the body's action schema, whereas prosthetics like rubber hands are incorporated into the body image itself. Contrary to this dichotomy, recent research demonstrated that chopsticks can be embodied perceptually during a modified version of the rubber hand illusion (RHI) in which tools are held by the rubber hand and by the participant. In the present research, two experiments examined tool morpho-functional (tool output affordance, e.g., precision grasping) and sensorimotor (tool input, e.g., precision grip) match as a mechanism for this tool-use dependent change to the body image. Proprioceptive drift in the RHI occurred when the tool's output and the user's input matched, but not when this match was absent. This suggests that this factor may be necessary for tools to interact with the body image in the RHI.

Firestone & Scholl (F&S) assume that pure perception is unaffected by cognition. This assumption is untenable for definitional, anatomical, and empirical reasons. They discount research showing nonoptical influences on visual perception, pointing out possible methodological “pitfalls.” Results generated in multiple labs are immune to these “pitfalls,” suggesting that perceptions of physical layout do indeed reflect bioenergetic resources.

We examined how observers use one aspect of their own morphology, height, when judging the physical characteristics of other people. To address this, participants judged the heights of people as they walked past. We tested the hypothesis that differences between participant and target height account for systematic patterns of variability and bias in height estimation. Height estimate error and error variability increased as the difference between participant height and target height increased, suggesting that estimates are scaled to observers' heights. Furthermore, participants' height estimates were biased toward two standards, demonstrating classic category effects. First, estimates were biased toward participants' own heights. Second, participants biased height estimates toward the average height of the target distribution. These results support past research on using both the body and categorical information to estimate target properties but extend to real-world situations involving interactions with moving people, such as height judgments provided during eyewitness testimony.

Natural environments are typically judged to be more restorative than built environments in terms of fostering recovery from stress or buffering against resource depletion. But this comparison tends to be categorical – nature versus built environments – and consequently, questions remain regarding the restorative potential of environments that do not fit into these categories. Furthermore, individual differences in evaluations of perceived restorative potential is not well understood. In Study 1, participants rated the perceived restorative potential of environments that ranged on a continuum from natural to built. Environmental attributes and individual differences were measured to predict perceived restorative potential. In Study 2, we measured the relationship between self-reported need-for-restoration and perceived restorative potential. The results support an account of perceived restorative potential that emphasizes the importance of visual appeal, naturalness, and an absence of people as important environment dimensions. These factors are influenced very little by assessed individual differences other than perceived need-for-restoration.

When humans perceive the environment, angular units of visual information must be transformed into units appropriate for the specification of such parameters of surface layout as extent, size, and orientation. Our embodied approach to perception proposes that these scaling units derive from the body. For example, hand size is relevant for scaling the size of a strawberry, whereas an extent across a meadow is scaled by the amount of walking required to traverse it. In his article, Firestone (2013, this issue) argued that our approach is wrong; in fact, he argued that it must be wrong. This reply to Firestone’s critique is organized into three parts, which address the following questions: (a) What is the fundamental question motivating our approach? (b) How does our approach answer this question? (c) How can we address Firestone’s arguments against our approach? A point-by-point critique of Firestone’s arguments is presented. Three conclusions are drawn: (a) Most of Firestone’s arguments reflect a misunderstanding of our approach, (b) none of his arguments are the fatal flaws in our approach that he believes them to be, and (c) there are good reasons to believe that perception—just like any other biological function—is a phenotypic expression.

Experimental research shows that there are perceived and actual benefits to spending time in natural spaces compared to urban spaces such as reduced cognitive fatigue, improved mood, and reduced stress. Whereas past research has focused primarily on distinguishing between distinct categories of spaces (i.e., nature versus urban), less is known about variability in perceived restorative potential of environments within a particular category of outdoor spaces, such as gardens. Conceptually, gardens are often considered to be restorative spaces and to contain an abundance of natural elements, though there is great variability in how gardens are designed that might impact their restorative potential. One common practice for classifying gardens is along a spectrum ranging from “formal or geometric” to “informal or naturalistic”, which often corresponds to the degree to which built or natural elements are present, respectively. In the current study, we tested whether participants use design informality as a cue to predict perceived restorative potential of different gardens. Participants viewed a set of gardens and rated each on design informality, perceived restorative potential, naturalness, and visual appeal. Participants perceived informal gardens to have greater restorative potential than formal gardens. In addition, gardens that were more visually appealing and more natural-looking were perceived to have greater restorative potential than less visually appealing and less natural gardens. These perceptions and precedents are highly relevant for the design of gardens and other similar green spaces intended to provide relief from stress and to foster cognitive restoration.

Influences on the perception of affordances (i.e., opportunities for actions) have been primarily studied by manipulating the functional morphology of the body. However, affordances are not just determined by the functional morphology of the perceiver, but also by the physiological state of the perceiver. States of anxiety have been shown to lead to marked changes in individuals' physiological state and their behaviour. To assess the influence of emotional state on affordance perception, the perception of action capabilities in near space was examined after participants completed an anxiety-provoking task. Anxiety was induced immediately prior to tasks that assessed participants' perceived reaching ability in Experiment 1, grasping ability in Experiment 2, and the ability to pass their hands through apertures in Experiment 3. Results indicated that those participants who experienced changes in anxiety underestimated their reaching, grasping, and passing ability compared to non-anxious participants. In other words, anxious participants were more conservative in their estimations of their action capabilities. These results suggest that anxiety influences the perception for affordances in near space and are consistent with the notion that anxiety induces withdrawal behaviours.

Individuals with autism spectrum disorders (ASDs) have known impairments in social and motor skills. Identifying putative underlying mechanisms of these impairments could lead to improved understanding of the etiology of core social/communicative deficits in ASDs, and identification of novel intervention targets. The ability to perceptually integrate one's physical capacities with one's environment (affordance perception) may be such a mechanism. This ability has been theorized to be impaired in ASDs, but this question has never been directly tested. Crucially, affordance perception has shown to be amenable to learning; thus, if it is implicated in deficits in ASDs, it may be a valuable unexplored intervention target. The present study compared affordance perception in adolescents and adults with ASDs to typically developing (TD) controls. Two groups of individuals (adolescents and adults) with ASDs and age-matched TD controls completed well-established action capability estimation tasks (reachability, graspability, and aperture passability). Their caregivers completed a measure of their lifetime social/communicative deficits. Compared with controls, individuals with ASDs showed unprecedented gross impairments in relating information about their bodies' action capabilities to visual information specifying the environment. The magnitude of these deficits strongly predicted the magnitude of social/communicative impairments in individuals with ASDs. Thus, social/communicative impairments in ASDs may derive, at least in part, from deficits in basic perceptual-motor processes (e.g. action capability estimation). Such deficits may impair the ability to maintain and calibrate the relationship between oneself and one's social and physical environments, and present fruitful, novel, and unexplored target for intervention.

According to the embodied approach to visual perception, individuals scale the environment to their bodies. This approach highlights the central role of the body for immediate, situated action. The present experiments addressed whether body scaling--specifically, eye-height scaling--occurs in memory when action is not immediate. Participants viewed standard targets that were either the same height as, taller than, or shorter than themselves. Participants then viewed a comparison target and judged whether the comparison was taller or shorter than the standard target. Participants were most accurate when the standard target height matched their own heights, taking into account postural changes. Participants were biased to underestimate standard target height, in general, and to push standard target height away from their own heights. These results are consistent with the literature on eye-height scaling in visual perception and suggest that body scaling is not only a useful metric for perception and action, but is also preserved in memory.

We examined whether the apparent size of an object is scaled to the morphology of the relevant body part with which one intends to act on it. To be specific, we tested if the visually perceived size of graspable objects is scaled to the extent of apparent grasping ability for the individual. Previous research has shown that right-handed individuals perceive their right hand as larger and capable of grasping larger objects than their left. In the first 2 experiments, we found that objects looked smaller when placed in or judged relative to their right hand compared to their left. In the third experiment, we directly manipulated apparent hand size by magnifying the participants' hands. Participants perceived objects to be smaller when their hand was magnified than when their hand was unmagnified. We interpret these results as demonstrating that perceivers use the extent of their hands' grasping abilities as "perceptual rulers" to scale the apparent size of graspable objects. Furthermore, hand size manipulations did not affect the perceived size of objects too big to be grasped, which suggests that hand size is only used as a scaling mechanism when the object affords the relevant action, in this case, grasping.

When locomoting in a physically challenging environment, the body draws upon available energy reserves to accommodate increased metabolic demand. Ingested glucose supplements the body's energy resources, whereas non-caloric sweetener does not. Two experiments demonstrate that participants who had consumed a glucose-containing drink perceived the slant of a hill to be less steep than did participants who had consumed a drink containing non-caloric sweetener. The glucose manipulation influenced participants' explicit awareness of hill slant but, as predicted, it did not affect a visually guided action of orienting a tilting palmboard to be parallel to the hill. Measured individual differences in factors related to bioenergetic state, such as fatigue, sleep quality, fitness, mood, and stress, also affected perception: lower energetic states were associated with steeper perceptions of hill slant. This research shows that the perception of the spatial layout of the environment is influenced by the energetic resources available for locomotion within it. Our findings are consistent with the view that spatial perceptions are influenced by bioenergetic factors.

Previous research on perceiving spatial layout has found that people often exhibit normative biases in their perception of the environment. For instance, slant is typically overestimated and distance is usually underestimated. Surprisingly, however, the perception of height has rarely been studied. The present experiments examined the perception of height when viewed from the top (e.g., looking down), or from the bottom (e.g., looking up). Multiple measures were adapted from previous studies of horizontal extents to assess the perception of height. Across all of the measures, a large, consistent bias was found: vertical distances were greatly overestimated, especially from the top. Secondary findings suggest that the overestimation of distance and size that occurs when looking down from a high place correlates with reports of trait- and state-level fear of heights, suggesting that height overestimation may be due, in part, to fear.

The current study tested whether height overestimation is related to height fear and influenced by images of falling. To assess perceptual biases, participants high (n = 65) versus low (n = 64) in height fear estimated the vertical extents of two balconies using a visual matching task. On one of the balconies, participants engaged in an imagery exercise designed to enhance the subjective sense that they were acting in a dangerous environment by picturing themselves falling. As expected, we found that individuals overestimated the balcony’s height more after they imagined themselves falling, particularly if they were already afraid of heights. These findings suggest that height fear may serve as a vulnerability factor that leads to perceptual biases when triggered by a stressor (in this case, images of falling).

Previous research has suggested that perceived distances are scaled by the action capabilities of the body. The present studies showed that when "reachability" is constrained due to a difficult grasp required to pick up an object, perceived distance to the object increases. Participants estimated the distances to tools with handle orientations that made them either easy or difficult to grasp with their dominant and nondominant hands. Right-handed participants perceived tools that were more difficult to grasp to be farther away than tools that were easier to grasp. However, perceived distance did not differ in left-handed participants. These studies suggest that, when reaching toward a target, the distance to that target is scaled in terms of how far one can effectively reach, given the type of reaching posture that is executed. Furthermore, this effect is modulated by handedness.

Spatial perception is sensitive to the energetic costs required to perform intended actions. For example, hills look steeper to people who are fatigued or burdened by a heavy load. Similarly, perceived distance is also influenced by the energy required to walk or throw to a target. Such experiments demonstrate that perception is a function, not just of optical information, but also of the perceiver’s potential to act and the energetic costs associated with the intended action. In the current paper, we expand on the notion of “cost” by examining perceived distance in patients diagnosed with chronic pain, a multifactorial disease, which is experienced while walking. We found that chronic pain patients perceive target distances to be farther away compared with a control group. These results indicate the physical, and perhaps emotional, costs of chronic pain affect spatial perceptions.

Controlling computers and other electronic devices using only one's thoughts is an exciting yet unlikely and distant reality for most people. However, for people with locked-in syndrome, their disabilities are so severe that they have no other alternatives. Applications that are consciously controlled using signals from the brain (called brain-computer interfaces, or BCIs) have been shown to restore some communication and environmental control for these individuals. Unfortunately, BCIs can be slow and tedious to learn or operate, reducing their effectiveness. This demonstration presents engaging BCI applications, including a video game and a digital painting program, that enable users to have fun while they improve their control over the brain signals required to use BCIs.

Perception is influenced by the perceiver's ability to perform intended actions. For example, when people intend to reach with a tool to targets that are just beyond arm's reach, the targets look closer than when they intend to reach without the tool (J. K. Witt, D. R. Proffitt, & W. Epstein, 2005). This is one of several examples demonstrating that behavioral potential affects perception. However, the action-specific processes that are involved in relating the person's abilities to perception have yet to be explored. Four experiments are presented that implicate motor simulation as a mediator of these effects. When a perceiver intends to perform an action, the perceiver runs a motor simulation of that action. The perceiver's ability to perform the action, as determined by the outcome of the simulation, influences perceived distance.

The goal of this study was to design a human-computer interface that would increase the memorability of information presented by providing context as compared with memory with no context. Our focus was in augmenting context-dependent memory because it is a powerful and often unexploited characteristic of human cognition. To amplify this cognitive strength, we built the InfoCockpit, which included a large screen containing projected images of places, a three-dimensional surround-sound system that played ambient noises congruent with the projected images, and a flat-panel monitor that served as the focal display for the presentation of the to-be-remembered information. Participants in our study learned and recalled information in either the InfoCockpit or a standard desktop environment. The InfoCockpit group demonstrated a 131% memory advantage. Contextual factors that were previously found to be effective in isolation created a large effect when presented in combination.

In perceiving spatial layout, the angular units of visual information are transformed into linear units appropriate for specifying size and extent. This derivation of linear units from angular ones requires geometry and a ruler. Numerous studies suggest that the requisite perceptual rulers are derived from the observer's body. In the case of walkable extents, it has been proposed that people scale distances to the bioenergetic resources required to traverse the extents relative to the bioenergetic resources currently available. The current study sought to rigorously test this proposal. Using methods from exercise physiology, a host of physiological measures were recorded as participants engaged in exercise on 2 occasions: once while provided with a carbohydrate supplement and once with a placebo. Distance estimates were made before and after exercise on both occasions. As in previous studies, the carbohydrate manipulation caused decreased distance estimates relative to the placebo condition. More importantly, individual differences in physiological measures that are associated with physical fitness predicted distance estimates both before and after the experimental manipulations. Results suggest that walkable distances are bioenergetically scaled.

Perception informs people about the opportunities for action and their associated costs. To this end, explicit awareness of spatial layout varies not only with relevant optical and ocular-motor variables, but also as a function of the costs associated with performing intended actions. Although explicit awareness is mutable in this respect, visually guided actions directed at the immediate environment are not. When the metabolic costs associated with walking an extent increase—perhaps because one is wearing a heavy backpack—hills appear steeper and distances to targets appear greater. When one is standing on a high balcony, the apparent distance to the ground is correlated with one's fear of falling. Perceiving spatial layout combines the geometry of the world with behavioral goals and the costs associated with achieving these goals.

Given that observing one's body is ubiquitous in experience, it is natural to assume that people accurately perceive the relative sizes of their body parts. This assumption is mistaken. In a series of studies, we show that there are dramatic systematic distortions in the perception of bodily proportions, as assessed by visual estimation tasks, where participants were asked to compare the lengths of two body parts. These distortions are not evident when participants estimate the extent of a body part relative to a noncorporeal object or when asked to estimate noncorporal objects that are the same length as their body parts. Our results reveal a radical asymmetry in the perception of corporeal and noncorporeal relative size estimates. Our findings also suggest that people visually perceive the relative size of their body parts as a function of each part's relative tactile sensitivity and physical size.

Distance perception seems to be an incredible achievement if it is construed as being based solely on static retinal images. Information provided by such images is sparse at best. On the other hand, when the perceptual context is taken to be one in which people are acting in natural environments, the informational bases for distance perception become abundant. There are, however, surprising consequences of studying people in action. Nonvisual factors, such as people's goals and physiological states, also influence their distance perceptions. Although the informational specification of distance becomes redundant when people are active, paradoxically, many distance-related actions sidestep the need to perceive distance at all.

Studies of locomotion in virtual environments assume that correct geometric principles define the relationship between walking speed and environmental flow. However, we have observed that geometrically correct optic flow appears to be too slow during simulated locomotion on a treadmill. Experiment 1 documents the effect in a head-mounted display. Experiment 2 shows that the effect is eliminated when the gaze is directed downward or to the side, or when the walking speed is slow. Experiment 3 shows that the effect is unchanged by stride length. Experiment 4 verifies that the effect is not attributable to image jitter. The change in perceived speed from straight ahead to side or down gaze coincides with a shift from expanding optic flow to lamellar flow. Therefore, we hypothesize that lamellar flow is necessary for accurate speed perception, and that a limited field of view eliminates this cue during straight-ahead gaze.

Recent research demonstrates neurologic and behavioral differences in people's responses to the space that is within and beyond reach. The present studies demonstrated a perceptual difference as well. Reachability was manipulated by having participants reach with and without a tool. Across 2 conditions, in which participants either held a tool or not, targets were presented at the same distances. Perceived distances to targets within reach holding the tool were compressed compared with targets that were beyond reach without it. These results suggest that reachability serves as a metric for perception. The 3rd experiment found that reachability only influenced perceived distance when the perceiver intended to reach. These experiments suggest that the authors perceive the environment in terms of our intentions and abilities to act within it.

In four experiments, we examined observers’ ability to locate objects in virtual displays while rotating to new perspectives. In Experiment 1, participants updated the locations of previously seen landmarks in a display while rotating themselves to new views (viewer task) or while rotating the display itself (display task). Updating was faster and more accurate in the viewer task than in the display task. In Experiment 2, we compared updating performance during active and passive self-rotation. Participants rotated themselves in a swivel chair (active task) or were rotated in the chair by the experimenter (passive task). A minimal advantage was found for the active task. In the final experiments, we tested similar manipulations with an asymmetrical display. In Experiment 3, updating during the viewer task was again superior to updating during the display task. In Experiment 4, we found no difference in updating between active and passive self-movement. These results are discussed in terms of differences in sources of extraretinal information available in each movement condition.

Berkeley proposed that space is perceived in terms of effort. Consistent with his proposal, the present studies show that perceived egocentric distance increases when people are encumbered by wearing a heavy backpack or have completed a visual-motor adaptation that reduces the anticipated optic flow coinciding with walking effort. In accord with Berkeley's proposal and Gibson's theory of affordances, these studies show that the perception of spatial layout is influenced by locomotor effort.

One important aspect of the pictorial representation of a scene is the depiction of object proportions. Yang, Dixon, and Proffitt (1999 Perception28 445–467) recently reported that the magnitude of the vertical – horizontal illusion was greater for vertical extents presented in three-dimensional (3-D) environments compared to two-dimensional (2-D) displays. However, because all of the 3-D environments were large and all of the 2-D displays were small, the question remains whether the observed magnitude differences were due solely to the dimensionality of the displays (2-D versus 3-D) or to the perceived distal size of the extents (small versus large). We investigated this question by comparing observers' judgments of vertical relative to horizontal extents on a large but 2-D display compared to the large 3-D and the small 2-D displays used by Yang et al (1999). The results confirmed that the magnitude differences for vertical over-estimation between display media are influenced more by the perceived distal object size rather than by the dimensionality of the display.

An embodied approach to the perception of spatial layout contends that the body is used as a ‘perceptual ruler’ with which individuals scale the perceived environmental layout. In support of this notion, previous research has shown that the perceived size of objects can be influenced by changes in the apparent size of hand. The size – weight illusion is a well known phenomenon, which occurs when people lift two objects of equal weight but differing sizes and perceive that the larger object feels lighter. Therefore, if apparent hand size influences perceived object size, it should also influence the object's perceived weight. In this study, we investigated this possibility by using perceived weight as a measure and found that changes in the apparent size of the hand influence objects' perceived weight.

When observers face directly toward the incline of a hill, their awareness of the slant of the hill is greatly overestimated, but motoric estimates are much more accurate. The present study examined whether similar results would be found when observers were allowed to view the side of a hill. Observers viewed the cross-sections of hills in real (Experiment 1) and virtual (Experiment 2) environments and estimated the inclines with verbal estimates, by adjusting the cross-section of a disk, and by adjusting a board with their unseen hand to match the inclines. We found that the results for cross-section viewing replicated those found when observers directly face the incline. Even though the angles of hills are directly evident when viewed from the side, slant perceptions are still grossly overestimated.

Previous studies found that it is easier for observers to spatially update displays during imagined self-rotation versus array rotation. The present study examined whether either the physics of gravity or the geometric relationship between the viewer and array guided this self-rotation advantage. Experiments 1-3 preserved a real or imagined orthogonal relationship between the viewer and the array, requiring a rotation in the observer's transverse plane. Despite imagined self-rotations that defied gravity, a viewer advantage remained. Without this orthogonal relationship (Experiment 4), the viewer advantage was lost. We suggest that efficient transformation of the egocentric reference frame relies on the representation of body-environment relations that allow rotation around the observer's principal axis. This efficiency persists across different and conflicting physical and imagined postures.

The visual system historically has been defined as consisting of at least two broad subsystems subserving object and spatial vision. These visual processing streams have been organized both structurally as two distinct pathways in the brain, and functionally for the types of tasks that they mediate. The classic definition by Ungerleider and Mishkin labeled a ventral "what" stream to process object information and a dorsal "where" stream to process spatial information. More recently, Goodale and Milner redefined the two visual systems with a focus on the different ways in which visual information is transformed for different goals. They relabeled the dorsal stream as a "how" system for transforming visual information using an egocentric frame of reference in preparation for direct action. This paper reviews recent research from psychophysics, neurophysiology, neuropsychology and neuroimaging to define the roles of the ventral and dorsal visual processing streams. We discuss a possible solution that allows for both "where" and "how" systems that are functionally and structurally organized within the posterior parietal lobe.

In a series of experiments, we delimited a region within the vertical axis of space in which eye height (EH) information is used maximally to scale object heights, referred to as the “zone of eye height utility” (Wraga, 1999b Journal of Experimental Psychology, Human Perception and Performance25 518–530). To test the lower limit of the zone, linear perspective (on the floor) was varied via introduction of a false perspective (FP) gradient while all sources of EH information except linear perspective were held constant. For seated (experiment 1a) observers, the FP gradient produced overestimations of height for rectangular objects up to 0.15 EH tall. This value was taken to be just outside the lower limit of the zone. This finding was replicated in a virtual environment, for both seated (experiment 1b) and standing (experiment 2) observers. For the upper limit of the zone, EH information itself was manipulated by lowering observers' center of projection in a virtual scene. Lowering the effective EH of standing (experiment 3) and seated (experiment 4) observers produced corresponding overestimations of height for objects up to about 2.5 EH. This zone of approximately 0.20–2.5 EH suggests that the human visual system weights size information differentially, depending on its efficacy.