NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Gravitational Acceleration as a Cue for Absolute Size and DistanceWhen an object's motion is influenced by gravity, such as the rise and fall of a thrown ball, the vertical component of acceleration is roughly constant at 9.8 m/sec2. In principle, an observer could use this information to estimate the absolute size and distance of the object (Saxberg, 1987a; Watson, Banks, von Hofsten, & Royden, 1992). In three experiments, we examined the ability to utilize the size and distance information provided by gravitational acceleration. Observers viewed computer simulations of an object rising and falling on a trajectory parallel to the gravitational vector. The simulated objects were three balls of different diameters presented across a wide range of simulated distances. Observers were asked to identify which ball was presented and the distance at which it was presented. The results of Experiment 1 showed that size and distance judgments were significantly better than chance, but not as accurate as expected if the information contained in the dynamics of free fall were used fully utilized. The results of Experiment 2 showed that acceleration information is used, but that observers can also make use of velocity information. Finally, the results of Experiment 3 showed that observers can use projected size information, but that their size and distance judgments are much more accurate when motion information is present as well. These results show that observers can use the information in the dynamics of free fall to estimate absolute size and distance, but their estimates are not as accurate as they could be if the information were used effectively.
Document ID
20020006041
Acquisition Source
Ames Research Center
Document Type
Preprint (Draft being sent to journal)
Authors
Hecht, Heiko
(NASA Ames Research Center Moffett Field, CA United States)
Kaiser, Mary K.
(NASA Ames Research Center Moffett Field, CA United States)
Banks, Martin S.
(California Univ. Berkeley, CA United States)
Hart, Sandra G.
Date Acquired
August 20, 2013
Publication Date
January 1, 1994
Subject Category
Physics (General)
Funding Number(s)
PROJECT: RTOP 538-04-11
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

Available Downloads

There are no available downloads for this record.
No Preview Available