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PubMed1995

Coincident timing by nondisabled, mentally retarded, and traumatic brain-injured individuals under varying target-exposure conditions.

Coincident timing by 15 nondisabled individuals, 15 mentally retarded and 15 traumatically brain injured was measured under varying target-exposure conditions. Absolute constant error, constant error, and variable error were analyzed in separate repeated-measures analyses of variance for early performance (first block of practice), late performance (last block of practice), and retention (last block of retention). Subjects with mental retardation displayed the least accurate and most variable coincident-timing responses. Nondisabled subjects were most influenced by target-exposure time; subjects with traumatic brain injury were most influenced by target-viewing distance; and subjects with mental retardation were most influenced by a combination of target velocity and target-viewing distance. Subjects with mental retardation displayed a too-early response bias, while nondisabled subjects tended to have a too-late response bias. Individuals with traumatic brain injury had a variable response bias.

Acceleration↗
PubMed1995

Dextrality and eye position in putting performance.

The relationship between eye and hand dominance and the relative positioning of the ball with respect to the subjects' eyes on putting performance was investigated. Twenty-four pure dextral (right-eyed and right-handed) and 24 cross-dextral (left-eyed and right-handed) novice golfers were randomly assigned to putt at a target 3.66 m away in two conditions, eyes focused directly over the ball and eyes positioned midway between their feet and the ball, i.e., eyes positioned 5 cm closer to their feet. The analysis indicated a significant interaction for dextrality and the relative position of the eyes during putting. Pure dextral golfers demonstrated less absolute error and less variable error in their putting performance when they focused their eyes midway between the ball and their feet than when they positioned their eyes directly over the ball. No differences in error scores were found for cross-dextrals across the two putting conditions.

Adolescent↗
PubMed1995

Effect of orientation in haptic reproduction of line length.

We investigated the accuracy of haptic reproduction of line length and whether accuracy is influenced by line orientation. 13 blindfolded subjects felt along different line lengths at various orientations in the horizontal plane, then reproduced the line lengths in the same orientation as that felt. Efforts were made to equate learning and reproductive scanning movements. Reproductions of line lengths were a nonveridical power function of their true lengths, but the power function exponents did not differ across spatial orientations. It was concluded that people can encode line lengths across spatial orientations by a common power function if care is taken to equate proprioceptive information across learning and reproduction.

Adult↗
PubMed1996

Specificity and variability of practice with young children.

It has previously been suggested that paradigms investigating schema theory should include tests of the effects of variability of practice on tasks experienced during the acquisition of learning. The present aim was to test this effect using a sports-related task. Two groups of children (n = 13 each) aged between 3 and 5 yr. old were pretested on an aiming task. They then received ten practice trials per day for ten days. One group (designated the specific group) practised only at the specified target distance, while another group (designated the specific plus variable group) practised at the target distance and at distances around the target. At the end of the practice period both groups were again tested. The data were analysed for distance and lateral errors, using two-way (group x time) analyses of covariance with one repeated measure on the latter factor. The interaction of groups x time was significant for the distance errors, indicating that at the end of the practice period the specific plus variable group had improved more than the specific group. This finding extends previous work on a similar variability paradigm to a sports-related setting.

Child Development↗
PubMed1997

Effects of figure context on the apparent length of a line.

This study investigated the effects of figure context on the apparent length of a line. In Exp. 1, ten participants were asked to adjust the length of a comparison line to match a standard line enclosed within a rectangle. The participants consistently overestimated the length of the standard line, demonstrating the stretching effect of figure context on the apparent length of a line. In Exp. 2 (12 participants), the size of the context figure was varied and it had no significant influence on the magnitude of the context effect. In Exp. 3 (nine participants), the context effect was shown not only for squares and rectangles but also for other shapes of figures such as circles and 5-pointed stars. We discuss the possible mechanism of the figure-context effect within Gregory's (1970, 1978) misapplied constancy theory of visual illusions.

Distance Perception↗
PubMed1997

The organization of visual objects: randomness.

A method was described for determining whether or not a pattern of visual objects is arranged randomly. Based on distance to nearest neighbor, it includes three conditions and is designed to avoid Type I errors. Examples were given, and comparisons were made with other methods.

Distance Perception↗
PubMed1997

Speed and accuracy of eye-gaze pointing.

The current experiment examined the speed-accuracy trade-off of saccadic movement between two targets. Ten subjects looked alternately at two targets as fast and as accurately as possible for 2 min. under different conditions of target size, distance between targets, and direction of eye movement. Saccadic movement of the left eye was tracked and recorded with an infrared eye monitoring device to compute the starting position, ending position, and duration of each saccadic movement. Eye-movement time was significantly related to target size and distance between targets, but the speed-accuracy trade-off was significantly different from that predicted by Fitts' Law. Reaction time was not significantly changed by the direction of eye movement.

Adult↗
PubMed1998

Similar Müller-Lyer effects from operant and comparison response modes.

A one-sided (monopole) version of the Müller-Lyer was used to assess the effect of response mode on the metric distortion associated with the illusion. Two different response modes were tested for comparability. The Operant Mode required the judgment of stimulus span to be indicated by marking a dot on the test page. The Comparison Mode required judgment of equality of two adjoining prepositioned spans. The perceptual effects with the comparison procedure are known to consist of underestimation of spans which are bounded by concave fin-sets and over-estimation of spans which are bounded by convex fin-sets. The question is whether the motor demands of the operant task produce an additional source of metric bias. Analysis indicate a very high correlation of judgments for the two modes of testing. Also, data with either mode of responding closely fit a linear model of the effect, and the model provides comparable index values for the concave and convex versions. These results should mitigate concern about potential motor bias from the operant method and encourage its use as a more efficient procedure for assessing metric distortion.

Distance Perception↗
PubMed1999

Contribution of stimulus attributes to errors in duration and distance judgments--a developmental study.

In Matsuda's 1996 study, 4- to 11-yr.-old children (N = 133) watched two cars running on two parallel tracks on a CRT display and judged whether their durations and distances were equal and, if not, which was larger. In the present paper, the relative contributions of the four critical stimulus attributes (whether temporal starting points, temporal stopping points, spatial starting points, and spatial stopping points were the same or different between two cars) to the production of errors were quantitatively estimated based on the data for rates of errors obtained by Matsuda. The present analyses made it possible not only to understand numerically the findings about qualitative characteristics of the critical attributes described by Matsuda, but also to add more detailed findings about them.

Child↗
PubMed1999

Standing distance in climbability of stairs.

The purpose of this experiment was to make a preliminary examination of the distance one needs to stand from a stair to successfully climb up without using arms for support. Using an adjustable stair structure to create different heights of risers, a group of 10 tall and of 10 short participants made perceptual judgments and physical attempts at heights that represented 83% and 93% of each group's mean leg length. Choice of maximum and minimum distance from the stair was measured for each participant. Analysis showed that perceptual judgments and physical capabilities were highly correlated (tall: Pearson r = .92); short: Pearson r = .93). Moreover, the ability to climb the two heights depended on the standing distance from the stair. The findings suggest that standing distance may be a consideration in stair climbing and that stair height alone may not be sufficient to specify climbability.

Adult↗
PubMed1999

Attention and estimated line length.

Whether attention affects the estimated length of a line has been debated for a long time. Some authors have found estimated length to increase with attention; others have found that it decreased. The present study further investigated this problem with two experiments. The first confirmed that estimated length decreased with attention; however, this result had low reliability. The second experiment indicated that estimated length significantly decreased with attention for some participants and significantly increased for others. This finding accounts for the low reliability of the first experiment and for the conflicting results of previous studies. Implications of opposite effects of attention for models of sensory intensity are discussed. An interpretation of these effects in terms of response preferences is proposed.

Attention↗
PubMed1999

Shadows as sources of cues for distance of shadow-casting objects.

Shadows are neglected sources of information about shadow-casting objects' distance (location). In an experiment using real shadows, participants judged the distance of two rods, either with shadows (illumination from the left) or without shadows. Without shadows, a thin rod raised slightly above the surface was incorrectly judged to be more distant than a thick rod, but with shadows the thin rod was accurately judged to be closer. For judgments to be correct, shadows had to overwhelm competing height and stimulus-size cues. Exp. II involved nonoverlapping shadows produced by a light placed in front of the rods. Again, without shadows the thin-elevated rod was incorrectly judged to be more distant, but with shadows it was correctly judged to be closer. Exp. III involved two sets of thick and thin elevated rods and frontal lighting. Judgments were accurate when shadows were present but inaccurate when shadows were absent. Experiments conducted through the American Psychological Society Web-research site replicated results of Exp. I, II, and III. A final Web experiment replicated results of the others, but with shadows produced by illumination from the right. Three properties of shadows--angles, interposition, and positioning--are possible sources of distance information associated with cast shadows.

Cues↗
PubMed2000

Decrement in the horizontal-vertical illusion: are subjects aware of their increased accuracy?

47 subjects adjusted the extended vertical lines of 20 inverted-T figures to make them appear equal to a horizontal line and rated the confidence in their accuracy after each trial. One group viewed figures of varying sizes, a second group viewed figures of standard size, and a third group viewed figures of standard size but received feedback on their accuracy immediately after completing Trial 5. Except for a significant increase in accuracy on Trial 6 for the Feedback Group, there were no differences in performance among groups. Subjects made the vertical line significantly shorter than the horizontal line on initial trials but their accuracy improved over trials. In contrast, there was no consistent increase in confidence, and several analyses indicated that confidence ratings were unrelated to accuracy. These results suggest that the subjects were unaware of the decrement in illusion that occurred over trials.

Achievement↗
PubMed2000

Angles of shadows as cues for judging the distance of shadow casting objects.

40 participants were presented the six possible comparisons of four pictures of cylinders and their shadows. For each comparison, each participant was to decide which cylinder was most distant from a reference point. Overall 15 of the participants got all six judgments correct, an outcome that is exceedingly unlikely by chance.

Adult↗
PubMed2000

Sex differences and action scaling in overhead reaching.

Specifications of affordances is independent of the anthropometric scale of the perceiver. It is therefore predicted that sex differences disappear when perceptual performance is scaled relative to the relevant physical properties of the system formed by performer and environment in a particular action. 24 women and 30 men were compared for their ability to perceive the boundaries for overhead reaching for a ball suspended above them. Perceived and actual maximum action boundaries were measured in two height conditions, with and without wearing 15-cm high blocks under their feet. On average the men reached higher than the women; however, when perceived maximum reachable height was expressed as a ratio of actual maximum reachable height, the difference between the groups disappeared. The participants showed an identical fit between environment and performer in both height conditions. The results indicate that the specification of affordances for overhead reaching is independent of the height and the sex of the performer.

Adult↗
PubMed2000

Psychological factors and sex differences in acceptance of monovision.

49 participants, adapted to using contact lenses, completed a battery of psychological tests to examine differences between persons who were successful in wearing monovision lenses for presbyopia and those who were unsuccessful. Although visual performance and requirements strongly affect participants' satisfaction with monovision lenses, personality characteristics and visual processing styles appear to in fluence the percentage of full-time wear. Of the participants, 41% (20 of 49) ultimately rejected monovision for a variety of both visual and psychological reasons. Sex differences were evidenced in the psychological variables correlated to monovision lens wear. Analysis indicated that men scoring as introverts rejected monovision while women with difficulty perceiving a visual pattern against visual background noise had difficulty adapting to monovision and exhibited shorter wearing times.

Accommodation, Ocular↗
PubMed2000

The tau and anti-tau effects in successively presented stimuli.

It was confirmed by the reproduction method with 20 adults that (a) the tau effect, i.e., the greater the temporal separation between successively presented stimuli with a constant spatial interval, the greater the apparent spatial interval, occurred, especially in the situation in which the participants were assumed to form a set easily using temporal interval as the cue for spatial interval estimation, and (b) the anti-tau effect occurred in the special situation in which the participants were assumed to form a set using speed of an imaginary movement as the cue for it. These findings supported the hypothesis of "cue-selection sets."

Adolescent↗
PubMed2001

The Poggendorff illusion: effect of distance between the parallel lines.

43 subjects observed Poggendorff figures with transverse line segments at a constant distance while the parallels were positioned closer or farther apart. At closer distances, no illusion occurred; at farther distances, the illusion diminished. The illusion no longer occurred when the parallels were located beyond the outside end of the transverse lines. Since illusions occurred only when the parallels physically touched the transverse line, this research emphasizes the importance of the intersection of figural elements in the production of the Poggendorff illusion.

Cues↗