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At least 685 records · Page 38Linked to original sources
PubMed2004

Categorical and metric distance information in mental representations derived from route and survey descriptions.

Descriptions with a route perspective take the addressee into the environment and give information on the position of objects relative to the changing position of the addressee. In contrast, descriptions with a survey perspective adopt a bird's-eye view and describe objects with respect to one another. The objective of the present study was to determine whether the perspective of a spatial description influences the extent to which categorical and metric distance is represented. We studied the characteristics of the representations that were constructed from route or survey descriptions with a recognition/priming task and a bird-flight distance comparison task. Spatial priming and symbolic distance effects were present after participants had studied a verbal description. The spatial priming effect indicated that objects in the environment were spatially organized according to some kind of distance (i.e., categorical or metric) in the representation of the listener. Furthermore, this organization was not dependent on whether the objects in a given prime-target relation were explicitly mentioned in the same sentence, or instead had to be inferred from the text. The presence of symbolic distance effects indicated that larger differences in metric distance were easier to compare than smaller differences, which is an effect that is also expected if actual metric distances on a visual map have to be compared. Therefore, further evidence was provided that people are able to create map-like spatial representations of verbal descriptions. We replicated previous findings that route and survey descriptions result in representations from which categorical spatial information is equally available. This study is the first to find evidence that a mental representation, which contains some analog spatial detail (i.e., metric distance), can be constructed from a description with a route perspective. Importantly, it should be noted that a relative advantage for survey descriptions over route descriptions did exist, suggesting that survey descriptions lead to spatial representations with a more fine-grained localization of the objects than route descriptions.

Adult↗
PubMed2006

The influence of trial-to-trial recalibration on sequential effects in cross-modality matching.

Sequential effects are examined in a cross-modality matching experiment where observers adjusted the loudness of a tone in response to presented lengths of a metal tape. In one condition, the initial level of the tone to be adjusted was the same as the final adjusted level of the previous trial, whereas in another condition, the tone to be adjusted was reset to a different level before each trial. A fit of the DeCarlo-Cross dynamic model shows that the primary effect of the manipulation was on a judgmental factor, with little or no effect on a perceptual factor. We suggest that starting a trial with the tone at the final adjusted level of the previous trial induced the observer to rely more heavily on the loudness-length pair of the previous trial as a frame of reference for relative judgment; we call this reliance trial-to-trial recalibration. In contrast, when the tone is set to a level independent of its value on the previous trial, there is virtually no effect of one trial on the next trial's performance, a result consistent with the observer maintaining a stable frame of reference. We argue that sequential effects are not unavoidable and that the technique described here adds to a growing list of methods for reducing or eliminating them.

Association↗
PubMed2001

Spatial range of illusory effects in Müller-Lyer figures.

The spatial range of the illusory effects in Müller-Lyer (M-L) figures was examined in three experiments. Experiments 1 and 2 assessed the pattern of bisection errors along the shaft of the standard or double-angle (experiment 1) and the single-angle (experiment 2) M-L figures: Subjects bisected the shaft and the resulting two half-segments of the shaft to produce apparently equal quarters, and then each of the quarters to produce eight equal-appearing segments. The bisection judgments of each segment were referenced to the segment's physical midpoints. The expansion or wings-out and the contraction or wings-in figures yielded similar patterns of bisection errors. For the standard M-L figures, there were significant errors in bisecting each half, and each end-quarter, but not the two central quarters of the shaft. For the single-angle M-L figures, there were significant errors in bisecting the length of the shaft, the half-segment, and the quarter, of the shaft adjacent to the vertex but not the second quarter from the vertex nor in dividing the half of the shaft at the open end of the figure into four equal intervals. Experiment 3 assessed the apparent length of the half-segment of the shaft at the open end of the single-angle figures. Length judgments were unaffected by the vertex at the opposite end of the shaft. Taken together, the results indicate that the length distortions in both the standard and single-angle M-L figures are not uniformly distributed along the shaft but rather are confined mainly to the quarters adjacent to the vertices. The present findings imply that theories of the M-L illusion which assume uniform expansion or contraction of the shafts are incomplete.

Adult↗
PubMed2006

Optimum view distance for laparoscopic surgery.

BACKGROUND: Proper visualization of the surgical field without fatigue is essential in laparoscopic surgery and reduces the risk of iatrogenic injuries. One of the important factors influencing visualization is the viewing distance between the surgeon and the monitor. This was the subject of the current investigation. METHODS: For this study, 14 surgeons participated in experiments designed to determine two working distances from a standard 34-cm (14 in. diagonal) cathode ray tube (CRT) monitor: (a) the maximum view distance permitting small prints of a near vision chart to be identified clearly by sight, (b) and the minimum view distance (of a standard resolution chart) just short of flicker, image degradation, or both. The range of the monitor optimal working distance for laparoscopic surgery was extrapolated from these data sets. RESULTS: The maximum view distance allowing identification of detail averaged 221 cm (range, 166-302 cm). The mean minimal view distance short of flicker/image degradation was 136 cm (range, 102-168 cm). The coefficient of variation for the two view distances was almost identical (18% vs 17%, respectively), and a frequency histogram confirmed the normality of the two data sets. Thus, for most surgeons, the extrapolated monitor view distances for laparoscopic surgery using a 14-in. diagonal (34-cm) monitor range from 139 to 303 cm (57-121 in.) for maximal distance viewing and from 90 to 182 cm (36-73 in.) for close-up viewing (i.e., a monitor optimal working distance ranging from 90 to 303 cm (36-121 in.). CONCLUSIONS: For most surgeons operating from a 14-in. diagonal CRT monitor, both the maximal and minimal (close-up) view distances are individually variable, but the surgeon should never be farther than 3 m (10 ft) or less than 0.9 m (3 ft) from the monitor. However, within limits, the maximal view distance increases with increasing monitor size. The limit for close-up distance is 0.9 m, irrespective of monitor size.

Clinical Competence↗
PubMed1994

Drivers' estimates of time to collision.

Drivers' estimates of time to collision were determined in a laboratory simulation using film segments made from a following vehicle approaching a lead vehicle, which was also in motion. Headway, approach speed, and viewing time were varied to make a total of 48 conditions. It was found that, provided the angular velocity subtended by the lead vehicle was above a threshold value of about .003 radians/sec, the driver was able to give reasonable estimates of time to collision. The standard deviation of the estimates varied linearly with the time to collision. Although drivers underestimated the time to collision when it was small, the large standard deviation shows the possibility of rear-end collisions due to poor estimation of time to collision, especially when the times for control action and vehicle deceleration are considered.

Acceleration↗
PubMed1996

Scaling of relative velocity between vehicles.

Data are presented on the ability of drivers to perceive and scale the relative velocity between their own and a lead vehicle. Experiments were carried out on four groups of subjects using Ekman's ratio-rating method. Only when the subtended angular velocity of the lead vehicle exceeded about 0.003 rad/s were the subjects able to scale the relative velocity. The threshold subtended angular velocity obtained in the experiments was very much affected by the ability of subjects to use the concept of a ratio-engineering students found this a simpler task than did subjects from the general population. The result of this was that the values used by engineering students were closer to the real values. The relative velocity was perceived non-linearly, with a Stevens' power law exponent of about 0.8. It was found that linear models gave as good a fit to the data. The implications of the results of the experiments are (i) traffic flow models that include human visual characteristics must consider the "dead zones" in response produced by thresholds of subtended angle change subtended angular velocity; (ii) it may be necessary to consider the non-linear relationship between perceived relative velocity and actual relative velocity; (iii) in overtaking, the driver will not be able to scale the speed of the oncoming vehicle as the subtended angular velocity will be below the threshold value at the time of making the decision to overtake.

Automobile Driving↗