Sequential Estimation of Points on a Psychometric Function

Wetherill, G. Barrie; Levitt, Harry

doi:10.1111/j.2044-8317.1965.tb00689.x

Cited by 1,140 publications

(597 citation statements)

References 5 publications

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“…As estimativas foram realizadas com o método psicofísico da escolha forçada (Santos et al, 2006;Wetherill & Levitt, 1965). Este método se baseia no cálculo da probabilidade de acertos consecutivos por parte do participante, ou seja, em cerca de 100 apresentações de escolhas entre os dois estímulos (onde se exige três acertos consecutivos e um erro para mudar o contraste), a freqüência radial (estímu-lo de teste) foi percebida, por exemplo, em 79% das vezes pelo voluntário.…”

Section: Procedimentounclassified

Sensibilidade ao contraste de freqüências radiais em crianças de 4 a 7 anos e adultos

Santos¹,

França²,

Simas³

2008

Psicol. Reflex. Crit.

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Resumo O objetivo deste trabalho foi medir a sensibilidade ao contraste para freqüências radiais (FSCr) de 0,25 a 2 cpg em crianças (4 a 7 anos) e adultos. Foram estimados limiares de contraste para 25 participantes (vinte crianças e cinco adultos jovens), utilizando o método psicofísico da escolha forçada. Os participantes apresentavam acuidade visual normal. Os resultados mostraram que as curvas (FSCr) de crianças de 4 a 7 anos melhoraram de forma significativa com a idade. Os resultados mostraram ainda que a FSCr de crianças de 7 anos é mais baixa do que a de adultos jovens. Estes resultados sugerem que o desenvolvimento da percepção visual de contraste para estímulos radiais ocorre gradualmente se prolongando além dos 7 anos. Palavras-chave: Sensibilidade ao contraste; desenvolvimento visual; crianças; freqüência radial; método da escolha forçada. AbstractThe aim of this work was to measure contrast sensitivity for radial frequencies (rCSF) in the range between 0.25-2 cpd in children (4 to 7 years of age) and young adults. Contrast thresholds were estimated for 25 participants (twenty children and five adults) using the psychophysical forced-choice method at low luminance levels. All the cts participants had normal acuity. The results showed that the curves (rCSF) of the 4, 5, 6 and 7 years old improved significantly with age. The results also showed that the rCSF for 7 year old children was lower than in young adults. These results suggest that the development of contrast sensitivity for radial stimuli increases gradually even after turning 7 years old.

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Section: Procedimentounclassified

Sensibilidade ao contraste de freqüências radiais em crianças de 4 a 7 anos e adultos

Santos¹,

França²,

Simas³

2008

Psicol. Reflex. Crit.

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“…Only contrast of the test frequency was increased or decreased according to a forced-choice method (36). Contrast of the background in both images of a stimulus pair was constant at 42%.…”

Section: Methodsmentioning

confidence: 99%

Narrow-band 1, 2, 3, 4, 8, 16 and 24 cycles/360º angular frequency filters

Simas

Santos

2002

Braz J Med Biol Res

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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.

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“…The methods for stimulus presentation most often used are Wetherill and Levitt's up and down staircase (Wetherill and Levitt 1965) and the ascending method of limits (Engen 1971). In the up and down staircase method, stimulus presentations are tailored to a subject's presumed threshold.…”

Section: Methods Of Stimulus Presentationmentioning

confidence: 99%

Setting occupational exposure limits in humans: contributions from the field of experimental psychology

Smeets

Kroeze

Dalton

2005

Int Arch Occup Environ Health

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Psychophysical methods from the field of experimental psychology are evaluated for their utility in the derivation of occupational exposure limits (OELs) for volatile chemicals based on acute sensory irritation in humans. The lateralization threshold method, which involves the localization of trigeminal vapor to the stimulated nostril, is evaluated for its underlying assumptions, reliability and validity. Whole body exposures, on the other hand, which involve the controlled, ambient exposure of human subjects to the irritant at one or a series of concentrations for an extended period are also discussed. It is concluded that the single-organ psychophysical method is largely resistant to response bias is practical and economical. However, its reliability and validity need further assessment. Whole body exposures, while having enhanced ecological validity, are more prone to demand characteristics, response bias, and subject beliefs than the traditional psychophysical procedures. An approach that involves the exposure of only the most sensitive organs such as the eyes and nose, via a mask or facebox, could facilitate the administration and alternation of odorant/irritant stimuli over a wide range of concentrations while enhancing ecological validity.

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Sequential Estimation of Points on a Psychometric Function

Abstract: A simple and efficient method of estimating points on the psychometric function, and thus of estimating absolute and difference limens, is described. An illustration of the method is given in which sensitivity to inter‐aural time differences is measured.

Cited by 1,140 publications

References 5 publications

Sensibilidade ao contraste de freqüências radiais em crianças de 4 a 7 anos e adultos

Sensibilidade ao contraste de freqüências radiais em crianças de 4 a 7 anos e adultos

Narrow-band 1, 2, 3, 4, 8, 16 and 24 cycles/360º angular frequency filters

Setting occupational exposure limits in humans: contributions from the field of experimental psychology

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