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PubMed1981

Experimenter naiveté and imaginal judgments.

Finke and Kurtzman report that fields of resolution increase with increases in the diameter of both perceived and imagined circular patterns. Their study apparently was conducted by an experimenter who was aware of the hypotheses under test. In contrast to these results, we find no such increase for imagined circular patterns when the experimenter is not aware of the experimental predictions, even though our subjects received imagery training as extensive as that used by Finke and Kurtzman. Our results cannot readily be attributed to differences between the experiments, other than those associated with experimenter naiveté, for we replicated Finke and Kurtzman's observations that (a) the fields of resolution in perception increase with both the diameter and the relative brightness of the patterns and (b) the fields of resolution in imagery do not increase with the relative brightness of the patterns. Our results also challenge Finke and Kurtzman's contentions that imagery and perception are treated as functionally equivalent at area-processing levels of the visual system but not at contrast-processing levels.

Discrimination Learning↗
PubMed1981

Perception of growth: a geometric analysis of how different styles of change are distinguished.

Although there have been many demonstrations that human observers can accurately recognize a variety of styles of change, such as rolling, walking, or growing, there are no existing theories capable of explaining how one style of change is distinguished from another. The present article offers a hypothesis that any recognizable style of change is uniquely specified by geometric invariants- the abstract properties of a visual display that are preserved by the change. In an effort to provide an empirical test of this hypothesis, several experiments involving the perception of growth were performed. Observers were required to make perceptual judgments of consequences of facial profiles, each of which was constructed by using a different mathematical transformation. The same pattern of results was obtained on both a free response task and a growth rating task: All transformations that were consistently identified as growth preserved the same geometric invariants.

Adolescent↗
PubMed1977

Perception of wholes and of their component parts: some configural superiority effects.

Theories of visual pattern recognition frequently assume that processing begins with an analysis of the pattern into component parts, which are often assumed to be line segments of particular orientations, lengths, positions, and curvatures. The present experiments measured discriminability of these simple parts when presented either in isolation or within configural contexts that provided no formal information useful for the discrimination. Certain contexts either impaired or did not affect performance. Other contexts were found, however, which dramatically improved discriminability. Thus, two patterns which differed only in a single part could be discriminated from each other more quickly than could their distinguishing parts shown in isolation. Further experiments suggest that this "configural superiority" effect influences perceptual components of processing rather than memorial components. The mechanism underlying configural superiority appears to be the detection of novel and distinguishing features, such as corners and intersections, which emerge when parts are placed in close proximity to each other. The outlines of a model for preattentive feature discrimination are presented.

Adult↗
PubMed1976

Recognition thresholds as a function of word length.

Several experiments investigated the effect of word length on recognition thresholds for both familiar English words and unfamiliar pseudowords, the thresholds measured both with and without a stimulus mask. For familiar English words, length had no effect either with or without a mask. For unfamiliar pseudowords, length had a dramatic effect both with and without a mask.

Discrimination, Psychological↗
PubMed1998

Female nurses' perceptions of acceptable female body size: an exploratory study.

A review of the literature indicated that women are often dissatisfied with their body size and weight. Feminist research has suggested that the images of the 'perfect' female body are socially constructed. The research conducted was exploratory in nature and aimed to focus on female nurses' perceptions of acceptable female body size. The choice of female nurses was deliberate in order to explore if they experienced dual pressures as health care workers and women. The study consisted of semistructured interviews which were conducted with a convenience sample of 10 nurses drawn from several specialities and hospitals throughout the Southern Health and Social Services Board (Northern Ireland). The research sample was small and therefore the findings cannot be generalized to the nursing profession as a whole. Many interesting questions were raised, which suggest that this topic is fertile ground for further research. The research findings indicate that assessment of female patients body size is arbitrary in nature and advice given to patients judged to be overweight is less than empirically based. Several of the nurses displayed discomfort with their role as intermediaries between patients and doctors when advising on weight control behaviours. In addition, there was strong evidence to suggest that there are discriminatory practices towards overweight female patients by doctors. The study concludes with recommendations for future practice and research in this area.

Adult↗
PubMed1990

A theory of phenomenal geometry and its applications.

The geometry of perceived space (phenomenal geometry) is specified in terms of three basic factors: the perception of direction, the perception of distance or depth, and the perception of the observer's own position or motion. The apparent spatial locations of stimulus points resulting from these three factors thereupon determine the derived perceptions of size, orientation, shape, and motion. Phenomenal geometry is expected to apply to both veridical and illusory perceptions. It is applied here to explain a number of representative illusions, including the illusory rotation of an inverted mask (Gregory, 1970), a trapezoidal window (Ames, 1952), and any single or multiple point stimuli in which errors in one or more of the three basic factors are present. It is concluded from phenomenal geometry that the size-distance and motion-distance invariance hypotheses are special cases of the head motion paradigm, and that proposed explanations in terms of compensation, expectation, or logical processes often are unnecessary for predicting responses to single or multiple stimuli involving head or stimulus motion. Two hypotheses are identified in applying phenomenal geometry. It is assumed that the perceptual localization of stimulus points determines the same derived perceptions, regardless of the source of perceptual information supporting the localizations. This assumption of cue equivalence or cue substitution provides considerable parsimony to the geometry. Also, it is assumed that the perceptions specified by the geometry are internally consistent. Departures from this internal consistency, such as those which occur in the size-distance paradox, are considered to often reflect the intrusion of nonperceptual (cognitive) processes into the responses. Some theoretical implications of this analysis of phenomenal geometry are discussed.

Attention↗
PubMed1992

Gravity as a monocular cue for perception of absolute distance and/or absolute size.

When the motion of an object is influenced by gravity (eg free fall, pendulum, wave motion), that influence may provide a cue to computing the absolute distance and/or size of the object. Formal analysis supports the claim that the distance and size of moving objects are generally computable with reference to the gravitational component of motion. Informal evidence from judgments of realism in films is consistent with this gravity-cue hypothesis.

Cues↗
PubMed1997

A change in viewpoint promotes use of height-in-picture as a depth cue in 5- to 7-year-olds' drawings of a simple depth relationship.

Height-in-picture emerges between 6 and 7 years of age in children's drawings as the first indication of portrayal of depth relationships, but can be promoted earlier by the use of a number of experimental manipulations. The present studies investigate whether changing, and hence drawing attention to, the child's viewpoint promotes use of height-in-picture. In the first study, 5/6- and 6/7-year-old children were asked to draw two blocks, arranged in depth. Following this, the child-array relationship was altered, either by moving the child through 90 degrees or by rotating the array through 90 degrees. Children then drew again what was now a left-right arrangement, whereupon the transformation was reversed and they made a final drawing. Only when children moved to a new standpoint was there a significant increase in vertical portrayal between first and third drawings. It was not simply the movement of the child that prompted use of height-in-picture because there was no such effect in conditions in which the child was moved but made an unrelated drawing from the new position. These results indicate that making viewpoint salient by asking for a drawing from a new position prompts young children to portray a simple depth relationship.

Age Factors↗