Narrow-band 1, 2, 3, 4, 8, 16 and 24 cycles/360º angular frequency filters
Braz. j. med. biol. res
;
35(2): 243-253, Feb. 2002. ilus, graf
Article
Dans Anglais
| LILACS
| ID: lil-303553
RESUMO
We measured human frequency response functions for seven angular frequency filters whose test frequencies were centered at 1, 2, 3, 4, 8, 16 or 24 cycles/360º using a supra-threshold summation method. The seven functions of 17 experimental conditions each were measured nine times for five observers. For the arbitrarily selected filter phases, the maximum summation effect occurred at test frequency for filters at 1, 2, 3, 4 and 8 cycles/360º. For both 16 and 24 cycles/360º test frequencies, maximum summation occurred at the lower harmonics. These results allow us to conclude that there are narrow-band angular frequency filters operating somehow in the human visual system either through summation or inhibition of specific frequency ranges. Furthermore, as a general result, it appears that addition of higher angular frequencies to lower ones disturbs low angular frequency perception (i.e., 1, 2, 3 and 4 cycles/360º), whereas addition of lower harmonics to higher ones seems to improve detection of high angular frequency harmonics (i.e., 8, 16 and 24 cycles/360º). Finally, we discuss the possible involvement of coupled radial and angular frequency filters in face perception using an example where narrow-band low angular frequency filters could have a major role
Texte intégral:
Disponible
Indice:
LILAS (Amériques)
Sujet Principal:
Vision
Limites du sujet:
Adulte
/
Humains
langue:
Anglais
Texte intégral:
Braz. j. med. biol. res
Thème du journal:
Biologie
/
Médicament
Année:
2002
Type:
Article
/
Congrès et conférence
/
descriptif de projet
Pays d'affiliation:
Brésil
Institution/Pays d'affiliation:
Universidade Federal de Pernambuco/BR
/
Universidade de Säo Paulo/BR
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