1985 - Sociedade Brasileira de Psicologia

(t.7.10.11).
œ %hod
observers. Ien observers between 17 and 27 years o1d partfctpated fn
this experlment.None had taken part ln 'any of the prevfous experimeatsy and
ùone had experfence w1th the method of magnltude esttmatlon.
Materials and Viewlng Sftuation - Tbe viewing sltuatton Qas a Iarge
open field 300 m tong and 30 m wfde and especfalty .landscaped to be
approprfate for thls kind of experiment. There were small trees and bushes
at the sfdes and at the far end.At tbe central tine of the ffeld. 9
distances were inconsptcuosly marked: 2.4,8,16,32.64:96,128. and 256 m. The
distances were marked by seven dtfferent-slzed yellow trfangtes. 0nt, one
triangte was placed at a tfmey and ft was ln the frontat-parallel plane.
Procedure - The method of free-modulus magnitude estimation w1th a
standard distance prevtdusly ffxed of 32 m vas used fn the two delays. Each
distance was exposed until the observer made a judgment.To reduce the tlme
foreacb observer usfng a large range ofdfstance each distancewas Judged
only once in a session.A11observer: served in the two detays and judged
again the same setof distances they had ffrstJudged.As ln Exp.lydelay
. was a within-subjects varfable.
4eal,:2A and p:acx âe a
The Psychophysfcal Function - For eaeh observer psychophysfcal pouer
functions were fitted by the oethod of lea t squares apptied to the
logarithlmically transformod physfcal distance and perceived dfstance. For
each observer were computed the exponent. the scale factor and the 12 .
An analysis of variance applfed to the tndividuat exponentg yfelded a nonsignfficant
effectsesslon and showed also thatsubjectswere a signfffcant
source. The mean exponents were .91. .90. and . 85 for Sessfons 1. 2 and 3..
respectfvely. These values are vlthln ehe range of exponene repo rted for
apparentdlstance estimated in a naturaloutdoor setting (1.3.10.11).
Intercorrelatfons of observers' Exponents - Pearson coefffcfents
vere computed between fndfvfdual exponents obtafned from the first sessloa
wfth those obtained from the second and atso wfth those obtafned from the '
tbtrd session. Also. the correlatlon between lndfvfdual exponents obtatned
from the second and thfrd sessfons vas eomputed.The Pearson ï were .84 for
581 '