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PubMed1976

Poggendorff illusion as a function of orientation of transversal and parallel lines.

Adult human subjects (8 male, 8 female undergraduates) with normal vision were required to judge various orientations of the Poggendorff illusion. The transversal and parallel line-segments of the illusion were manipulated to produce the orientations to be judged. Minimum illusion occured when the transversal line-segment was oriented 90 degrees with respect to true vertical or true horizontal. Magnitude of illusion increased as the transversal line-segment deviated from these positions. The findings suggested that there is a stability of horizontal and vertical orientations. In addition, the hypothesis that visual acuity plays a role in the perception of the Poggendorff illusion was proposed.

Adult↗
PubMed1981

Growth of apparent duration: effect of melodic and non-melodic tonal variation.

Time estimates of 12 intervals of 15 to 65 sec. duration were obtained from 30 subjects by one of two methods, magnitude estimation and cross-modal matching. Three kinds of sequences of musical notes were presented during stimulus intervals; repetitive, melodic, and random. Within all sequences, notes were of equal duration and with equal pauses between them. In all cases, the relationship between perceived and physical time is consistent with Stevens' power law. Exponents derived from both kinds of estimates were significantly affected by the content of the interval. Exponents derived for repetitive sequences were not different from 1 and were significantly larger than exponents derived from random or melodic sequences. These results are inconsistent with the view that the predictability, familiarity, or codability of event occurring in the stimulus interval is inversely related to the perceived duration of that interval. There is some indication that the effect of the content of the interval on judgments of duration varies with the magnitude of the duration being judged. Perhaps the relationship holds only within certain parameters and, when these are exceeded, other factors mask the effect. A two-process theory of time perception, one which considers these other factors and explains the present results, is proposed.

Humans↗
PubMed1976

Perception as a possible source of conservation: evidence for length conservation.

In conservation problems, it is commonly assumed that equivalence judgments are not facilitated by observation of the stimuli following transformation. The reverse is usually assumed to be the case. These assumptions were tested in a training experiment. Perceptual counterparts of a series of conservation of length tests were presented to subjects who were catagorized as conservers or nonconservers on conservations of length pretests, and to conservers and nonconservers given conservation of length training. Perceptual performance of the untrained nonconservers was significantly worse than that of the other 3 groups, that is, trained nonconservers, untrained conservers, and trained conservers. These findings are interpreted as consistent with the hypothesis that conservation is attained with the support of perception, not in spite of it.

Child↗
PubMed1994

The psychophysical power law and unilateral spatial neglect.

The relationship between objective measures and subjective experiences of sensory stimuli is described by a power law, psi = K phi beta, in which psi represents the psychological value and phi the physical value. The constant (K) and the exponent (beta) are empirically derived. This relationship is often assumed to correspond to properties of peripheral receptor sensory transduction. Patients with left-sided spatial neglect tend to bisect lines to the right of the objective midline. Line bisection bias was used as the dependent variable in how a patient with neglect and five normal subjects bisected lines of varying lengths. Analyzing these data as a power function accounted for over 99% of the variance in five different experimental conditions. The normal exponent matched the value expected from traditional psychophysical experiments of line length estimation, whereas the patient's exponent was diminished. The patient's data provide evidence for central nervous system participation in computations underlying psychophysical relationships. The notion that attentional and perceptual processes are closely linked was supported by the influence of attentional cuing on the power functions obtained in normal subjects. The descriptive precision of the power function uncovered qualitative variability in how normal subjects allocate attention across different spatial reference frames and demonstrated that this patient had a quantitative defect in directing attention across an allosteric reference frame, but a qualitative defect in directing attention across a viewer/environment reference frame.

Aged↗
PubMed2006

Effect of stimulus orderability and reinforcement history on transitive responding in pigeons.

Transitive responding in humans and non-human animals has attracted considerable attention because of its presumably inferential nature. In an attempt to replicate our earlier study with crows [Lazareva, O.F., Smirnova, A.A., Bagozkaja, M.S., Zorina, Z.A., Rayevsky, V.V., Wasserman, E.A., 2004. Transitive responding in hooded crows requires linearly ordered stimuli. J. Exp. Anal. Behav. 82, 1-19], we trained pigeons to discriminate overlapping pairs of colored squares (A+ B-, B+ C-, C+ D-, and D+ E-). For some birds, the colored squares, or primary stimuli, were followed by a circle of the same color (feedback stimuli) whose diameter decreased from A to E (Ordered Feedback group); these circles were made available to help order the stimuli along a physical dimension. For other birds, all of the feedback stimuli had the same diameter (Constant Feedback group). In later testing, novel choice pairs were presented, including the critical BD pair. The pigeons' reinforcement history with Stimuli B and D was controlled, so that the birds should not have chosen Stimulus B during the BD test. Unlike the crows, the pigeons selected Stimulus B over Stimulus D in both ordered and Constant Feedback groups, suggesting that the orderability of the post-choice feedback stimuli did not affect pigeons' transitive responding. Post hoc simulations showed that associative models [Wynne, C.D.L., 1995. Reinforcement accounts for transitive inference (TI) performance. Anim. Learn. Behav. 23, 207-217; Siemann, M., Delius, J.D., 1998. Algebraic learning and neural network models for transitive and non-transitive responding. Eur. J. Cogn. Psychol. 10, 307-334] failed to predict pigeons' responding in the BD test.

Animals↗
PubMed2002

Effect of background motion on line bisection performance in normal subjects.

Previous studies have demonstrated that optokinetic stimulation (OKS) influences line bisection (LB) performance in normal subjects and patients with hemispatial neglect. Since subjects were required to attend to stationary targets on a moving background, prior experimental designs might have induced an illusion of target motion or induced motion (IM) in a direction opposite the background. The current study tested whether the IM affects LB performance in normal subjects and how the speed of targets also influences LB. Thirty-two right-handed normal volunteers (aged 28.0 +/- 5.3 years) were asked to bisect stationary lines with a background of horizontal OKS. These stimuli were generated by computer displayed on a large screen via a beam projector. The OKS was varied according to direction (leftward or rightward) and speed (9.4 degrees/sec or 56.1 degrees/sec), producing 4 different experimental conditions. Mean bisection errors in all conditions were compared with a control condition with no background OKS. For each condition, subjects rated the degree of IM on a 5 point scale. With fast rate OKS, subjects reported minimal IM and LB errors were in the same direction as background motion, a finding that replicates previous studies. Conversely, the slow OKS rate caused subjects to report IM and resulted in deviation of the bisection mark in a direction opposite the background OKS. While this discrepancy between the slow and fast OKS conditions might be related to motion illusion, we did not find a direct correlation between the degree of IM and bisection errors and thus reasons for these results remain unexplained.

Adult↗
PubMed1999

More thoughts on perceiving and grasping the Müller-Lyer illusion.

It has been suggested that the insensitivity of the visuomotor system to various visual illusions is based on mechanisms in the so-called 'dorsal stream' of primate extrastriate cortex, which may depend upon binocular cues for their functions. The present study investigated the effects of binocular and monocular viewing on perception of and action to Müller-Lyer figures. Fourteen participants were required to match and grasp the shaft of a Müller-Lyer display under both viewing conditions. In the matching condition, participants were required to show the perceived extent of the central shaft of one of the two Müller-Lyer figures, using the extent of the gap between their finger and thumb. In the grasping task, participants were required to quickly and accurately reach out and grasp the central shaft of the specified Müller-Lyer figure. First, there was a striking effect of the illusion on the matching performance under both viewing conditions. However, the maximum grip aperture remained unaffected by the illusion figures. These results add to the theory of distinct modes of visual processing for perception and action. However, we did not find that grasping performance was affected by the illusion under monocular conditions. It is plausible that monocular depth cues distinct from those responsible for the illusion can successfully drive accurate grasping. Additional concerns regarding claims of action system resistance to the perceptual distortions of various illusions are discussed.

Adult↗
PubMed2002

Surface construal and the mental representation of scenes.

What distinguishes scenes from nonscenes? Photographs of objects on both naturalistic and blank backgrounds yielded boundary extension (BE: memory for unseen spatial expanse outside the picture's boundaries). However, line-drawn objects on blank backgrounds did not (Experiment 1). Perhaps the blank background was construed as depicting a real-world surface in the photograph condition but was construed as depicting nothing in the line-drawn condition. To change background construal, the authors used objects cut out of photographs; these were placed on blank backgrounds while viewers watched (Experiments 2 and 3). BE was eliminated. The authors propose that amodal continuation is a fundamental aspect of scene perception. However, not all pictures are scenes--only pictures construed as depicting a truncated view of a continuous world.

Adult↗
PubMed1998

Categorical perception effects induced by category learning.

The authors report a series of studies designed to determine whether effects similar to those observed in the innate categorical perception of color and phonemes are induced during the learning of simple unidimensional categories and more complex multidimensional ones. In Experiment 1 no evidence was found for such effects when stimuli varied on 1 dimension. Experiments 2 and 3 demonstrated a within-category compression effect but no between category expansion effect for stimuli varying in 2 dimensions. Compression only was also shown in Experiment 4, which used pictures of actual objects. Multidimensional scaling analyses illustrate how within-category compression without expansion was sufficient to produce categorical clustering of items in the similarity space. These analyses also show that learning changed the dimensional structure of similarity space. Results are compared with those from other studies exploring similar phenomena and with neural network simulations.

Adolescent↗
PubMed2007

How much does number matter to a monkey (Macaca mulatta)?

Although many animal species can represent numerical values, little is known about how salient number is relative to other object properties for nonhuman animals. In one hypothesis, researchers propose that animals represent number only as a last resort, when no other properties differentiate stimuli. An alternative hypothesis is that animals automatically, spontaneously, and routinely represent the numerical attributes of their environments. The authors compared the influence of number versus that of shape, color, and surface area on rhesus monkeys' (Macaca mulatta) decisions by testing them on a matching task with more than one correct answer: a numerical match and a nonnumerical (color, surface area, or shape) match. The authors also tested whether previous laboratory experience with numerical discrimination influenced a monkey's propensity to represent number. Contrary to the last-resort hypothesis, all monkeys based their decisions on numerical value when the numerical ratio was favorable.

Animals↗
PubMed1993

Referential set presentation effects on complementation by 6-year-olds.

What difficulties do children encounter when responding to complementation instructions? The responses of 50 children to six complementation requests were examined. For half of the children, the objects in the referential set were pooled, and for the other half, they were physically separated by category (pencils were presented in a pencil box, buttons in a sewing kit, and balls of yarn in a knitting basket). Reinforcing the identifying status of the semantic property by separating the objects into categories led to an increase in the number of responses bearing on the subset designated in the instructions (e.g., in response to "Give me everything that is not a black button," the children handed over only the nonblack buttons). In contrast, older children gave responses based on the entire set. The meaning attributed by children to object properties and the effects of that attribution on processing mode merit further study.

Adolescent↗