Perceived size of familiar objects and the theory of off-sized perceptions

In three experiments, I examined the claim (Gogel, 1969; Gogel & Newton 1969)that familiar objects viewed under reduced stimulus conditions frequently appear to be off-sized (i.e., larger or smaller.than normal). In Experiments 1 and 2, I presented images ofdifferent familiar objects, one at a time, at distances of .1. and 2 m from the observers. The images were normal-, large-, or small-sized versions of familiar objects, and the observers judged the perceived size of each object rela.tive to its familiar normal size. In Experiment 3, I presented normal-, large-, and small-sized versions of thesame familiar object at physical distances of 1 and 2 m. The pattern of size results was similar across the three experiments. In general, normal-sized objects appeared normal to small-sized at the 1-mdistance and small-sized at the 2-mdistance; small-sized objects appeared small-sized at the 1-m distance and even smaller at the 2-m distance; and large-sized objects appeared normal- to large-sized at the 1-m distance and normal- to small-sized at the 2-m distance. The distance results of Experiment 3 indicated that familiar size was an effective determinant of reported distance. These results are consistent with Gogel’s theory of off-sized perceptions and, more generally, with the claim that familiar size is not an important determinant of perceived size.     

The role of instructions and familiar size in absolute judgments of size and distance

The effects of familiar size and instructions (apparent, objective) on direct reports of size and distance were evaluated. Subjects estimated the size and distance of two different-sized playing cards or two unfamiliar stimuli under either apparent or objective instructions. The stimuli were presented successively at a distance of 5.48 m under reduced-cue conditions. The form of the instructions selectively influenced the effect of familiar size on absolute judgments of size and distance, with apparent instructions minimizing, and objective instructions promoting, familiar-size effects. The ratio of the distance judgments of the first to the second presented stimuli approximated the relative retinal sizes of the two objects under both apparent and objective instructions, while the ratio of size judgments tended to be either influenced by or independent of the object’s relative retinal sizes under apparent and objective instructions, respectively. These results are consistent with Gogel’s theory of off-size perception and, in particular, with the claim that, in comparison with apparent instructions, objective instructions are more likely to direct observers to base their judgments on cognitive, as opposed to perceptual, sources of spatial information.     

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.     

An indirect method of measuring perceived distance from familiar size

Two methods of measuring perceived distance as a function of familiar size were compared in five experiments. The method which uses the perception of motion concomitant with a motion of the head, unlike the method of verbal report, is considered to provide a measure of perceived distance that is unaffected by factors of cognitive distance. The results of the experiments indicate that although the perceived egocentric distance of an object can vary somewhat as a function of the cue of familiar size, the larger variation often found with verbal reports of distance is based upon cognitive, not perceptual, information. The cognitive information is interpreted as resulting from the perception of the object as off-sized and the observer’s assumption that the perceived size of an object will vary inversely with its physical distance.     

The role of instructions and familiar size in absolute judgments of size and distance.

The effects of familiar size and instructions (apparent, objective) on direct reports of size and distance were evaluated. Subjects estimated the size and distance of two different-sized playing cards or two unfamiliar stimuli under either apparent or objective instructions. The stimuli were presented successively at a distance of 5.48 m under reduced-cue conditions. The form of the instructions selectively influenced the effect of familiar size on absolute judgments of size and distance, with apparent instructions minimizing, and objective instructions promoting, familiar-size effects. The ratio of the distance judgments of the first to the second presented stimuli approximated the relative retinal sizes of the two objects under both apparent and objective instructions, while the ratio of size judgments tended to be either influenced by or independent of the object's relative retinal sizes under apparent and objective instructions, respectively. These results are consistent with Gogel's theory of off-size perception and, in particular, with the claim that, in comparison with apparent instructions, objective instructions are more likely to direct observers to base their judgments on cognitive, as opposed to perceptual, sources of spatial information.     

Categorical perception of familiar objects

We report three experiments where the categorical perception of familiar, three-dimensional objects was investigated. A continuum of shape change between 15 pairs of objects was created and the images along the continuum were used as stimuli. In Experiment 1 participants were first required to discriminate pairs of images of objects that lay along the shape continuum. Then participants were asked to classify each morph-image into one of two pre-specified classes. We found evidence for categorical perception in some but not all of our object pairs. In Experiment 2 we varied the viewpoint of the objects in the discrimination task and found that effects of categorical perception generalized across changes in view. In Experiment 3 similarity ratings for each object pair were collected. These similarity scores correlated with the degree of perceptual categorization found for the object pairs. Our findings suggest that some familiar objects are perceived categorically and that categorical perception is closely tied to inter-object perceptual similarity.     

Failure of familiar size to determine a metric for visually perceived distance

The use of knowledge of the familiar sizes of objects in determining the apparent distances of those objects is known as the familiar size cue to distance. If effective, this cue might be one of the factors responsible for supplying the metric (scalar) characteristics of perceptions of spatial extent within a visual display in which other information concerning scalar extents has been reduced to a minimum. Two groups of observers were presented with realistic objects of the same angular, but different assumed, sizes presented in such a cue-restricted display. Perceptions of size and distance within the display did not differ significantly as a function of the type of object initially presented. This result was consistent with the notion that scalar perceptions under these conditions probably are determined by a factor known as the specific distance tendency, rather than by the experiential factor of familiar size.     

Perceived size and distance as a perceptual conflict between two processing modes

Three different sized squares were successively presented at the same physical distance under three observational conditions which provided different information about distance in the visual field. The 60 observers in each observational condition were asked to give verbal absolute judgments of perceived size and perceived distance for each of the squares. The results showed that in a full-cue situation a ratio of perceived absolute sizes is equal to that of the corresponding visual angles, with perceived distances appearing equal to each other; in a reduced-cue situation an object of smaller perceived size is judged to be farther away than one of larger perceived size, with the observers tending to assume the two objects as the same object or identically sized objects. These results were analyzed in terms of the perceptual conflict between primary perception and secondary perception.     

Determining the orientation of depth-rotated familiar objects

How does the human visual system determine the depth-orientation of familiar objects? We examined reaction times and errors in the detection of 15° differences in the depth orientations of two simultaneously presented familiar objects, which were the same objects (Experiment 1) or different objects (Experiment 2). Detection of orientation differences was best for 0° (front) and 180° (back), while 45° and 135° yielded poorer results, and 90° (side) showed intermediate results, suggesting that the visual system is tuned for front, side and back orientations. We further found that those advantages are due to orientation-specific features such as horizontal linear contours and symmetry, since the 90° advantage was absent for objects with curvilinear contours, and asymmetric object diminished the 0° and 180° advantages. We conclude that the efficiency of visually determining object orientation is highly orientation-dependent, and object orientation may be perceived in favor of front-back axes.     

The effects of familiar size on judgments of size and distance: An interaction of viewing attitude with spatial cues

Two hypotheses about the effects of familiar size on judgments of size and distance, the cue-conflict hypothesis and the viewing-attitude hypothesis, were examined. In Experiment 1, observers estimated the size and distance of familiar targets with apparent or assumptive instructions under three different spatial cue conditions. In Experiment 2, observers performed tasks similar to those of Experiment 1 with no specific instructions. The main results were: (1) Assumptive instructions facilitate the effects of familiar size in both size and distance judgments, but reducing spatial cues does not, and (2) viewing attitude changes from the apparent to the assumptive when available spatial cues are reduced. Thus, it was concluded that the viewing-attitude hypothesis gives a better account of the effects of familiar size, but that the cue-conflict hypothesis cannot be abandoned, because the number of conflicting cues contributes to the formation of viewing attitude.     

Recognition thresholds for plane-rotated pictures of familiar objects

We investigated picture plane rotation effects on the minimum stimulus duration required to recognise pictures of familiar objects in a picture-word verification task. Participants made unspeeded responses, selecting from 126 written alternatives. Longer stimulus durations were needed to identify plane-misoriented views. These orientation effects were non-linear, arguing against a simple mental rotation account of compensation for plane misorientation in identification tasks. Orientation effects were found for almost all items, in particular including those labelled at the basic level (cf. Hamm, McMullen, 1998, Journal of Experimental Psychology: Human Perception and Performance 24, 413-426). We suggest that plane misorientation increases the difficulty of basic level as well as subordinate level identification unless only a small, visually dissimilar set of stimuli are presented. Errors in the task were analysed to provide an alternative, objective measure of perceived visual similarity, by assessing the number and nature of mistaken identifications made to a given target object. We propose that misorientation effects are best understood in terms of the effects of the perceived visual similarity of a target to its set of response alternatives rather than in terms of the level (basic or subordinate) at which the target is to be identified.     

Perceived size and perceived distance in stereoscopic vision and an analysis of their causal relations

Effects of visual angle and convergence upon the perceived sizes and perceived distances of a familiar object (playing card) and a nonrepresentational object (blank white card) were investigated by means of a projector stereoscope with polarizing filters. The results obtained with six Ss indicated that size estimates increased nearly proportionally as the visual angle increased and decreased nearly linearly as the convergence increased. Distance estimates decreased nearly linearly as either the visual angle or the convergence increased. The ratio of the size estimate to the distance estimate for a given visual angle was almost constant irrespective of convergence. In this sense, the size-distance invariance hypothesis held. No clear effect of familiarity was found. Partial correlations were used to discriminate direct and indirect causal relationships between the stimulus variables and perceptual estimates. Both perceived size and perceived distance were found to be determined directly by the two stimulus variables, but to be mutually related only indirectly.     

A stereo disadvantage for recognizing rotated familiar objects

We tested recognition of familiar objects in two different conditions: mono, where stimuli were displayed as flat, 2-D images, and stereo, where objects were displayed with stereoscopic depth information. In three experiments, participants performed a sequential matching task, where an object was rotated by up to 180° between presentations. When the 180° rotation resulted in large changes in depth for object components, recognition performance in the mono condition showed better performance at 180° rotations than at smaller rotations, but stereo presentations showed a monotonic increase in response time with rotation. However, 180° rotations that did not result in much depth variation showed similar patterns of results for mono and stereo conditions. These results suggest that in some circumstances, the lack of explicit 3-D information in 2-D images may influence the recognition of familiar objects when they are depicted on flat computer monitors.     

Learning of lists of properties related to familiar objects

Four groups of Ss simultaneously learn six-word lists that indicate common objects' properties. Words of each list may either all correspond to the same object (highest homogeneity level), or, inversely, correspond to six different objects (highest heterogeneity level), with two intermediate situations in between.The homogeneity of lists has a main effect upon learning. It is hypothesized that the object corresponding to the words of a list is used, when it is detected, as a federator for this words, and thus facilitates their recall. It is concluded there is a certain similarity between word lists corresponding to several properties of an object and taxonomic lists.     

Children's haptic and cross-modal recognition with familiar and unfamiliar objects

Five-year-old children explored multidimensional objects either haptically or visually and then were tested for recognition with target and distractor items in either the same or the alternative modality. In Experiments 1 and 2, haptic, visual, and cross-modal recognition were all nearly with familiar objects; haptic and visual recognition were also excellent with unfamiliar objects, but cross-modal recognition was less accurate. In Experiment 3, cross-modal recognition was also less accurate than within-mode recognition with familiar objects that were members of the same basic-level category. The results indicate that children's haptic recognition is remarkably good, that cross-modal recognition is otherwise constrained, and that cross-modal recognition may be accomplished differently for familiar and unfamiliar objects.     

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.