Psychophysics 心理物理学 Psychophysik Fechner (1860) Psychophysics 物理刺激 環境 心 物理量 明るい 暗い きれい 面白い 主観量 Psychophysics Baird & Noma (1978), p.13, Figure 2.1 1 Psychophysics Ernst H. Weber 1834 Psychophysics Gustav Theodor Fechner 1860 “Element der Psychophysik” 2 Psychophysics Stanley Smith (S. S.) Stevens Psychophysics Baird & Noma (1978) “Psychophysics is commonly defined as the quantitative branch of the study of perception, examining the relations between observed stimuli and responses and the reasons for those relations. This is, however, a very narrow view of the influence it has had on much of psychology. Since its inception, psychophysics has been based on the assumption that the human perceptual system is a measuring instrument yielding results (experiences, judgments, responses) that may be systematically analyzed. Because of its long history (over 140 years), its experimental methods, data analyses, and models of underlying perceptual and cognitive processes have reached a high level of refinement. For this reason, many techniques originally developed in psychophysics have been used to unravel problems in learning, memory, attitude measurement, and social psychology. In addition, scaling and measurement theory have adapted these methods and models to analyze decision making in contexts entirely divorced from perception” 3 Psychophysics Macmillan & Creelman (1991) “Detection theory is a general psychophysical approach to measuring performance. Its scope includes the everyday experimentation of many psychologists, social and medical scientists, and students of decision processes.” Green & Swets (1974) “The (signal detection) theory provides a means of analyzing the essential structure of the observer’s decisions in psychophysical tasks ... suggestions for appropriate procedure for data collection and analysis.” Psychophysics 心理物理学的測定法 感覚尺度構成法(sensory scaling) 感覚能力の測定 実験課題 検出(detection) 弁別(discrimination) 同定(identification) 尺度化(scaling) 4 Psychophysics 閾(threshold) • 絶対閾(absolute threshold)* *検出閾(detection threshold) • 弁別閾(discrimination threshold)# # 丁度可知差異(just noticeable difference, JND) 閾値測定法 1. 2. 3. 4. 調整法(method of adjustment) 極限法(method of limit) 恒常法(method of constant stimuli) 上下法(up-down method)* *段階法(staircase method)、適応法(adaptive method) Psychophysics 終了時点の刺激量=閾値 弁別では 閾値=|標準刺激量ー終了時点の比較刺激量| 1 2 3 4 ・・・ n 1 2 3 4 ・・・ n 上昇系列 下降系列 5 Psychophysics 心理測定関数 心理測定関数 P(Response) 1 0.75 0.5 0.25 0 0 2 4 6 Stimulus Magnitude Psychophysics 心理測定関数 Psychometric function 1 P(+) 0.75 0.5 0.25 0 1.7 1.8 1.9 2.0 2.1 2.2 2.3 Line length (relative) 6 Psychophysics A) 直線補間法 Psychometric function 1 P(+) 0.75 0.5 0.25 1.97 0 1.7 1.8 1.9 2.0 2.1 2.2 2.3 Line length (relative) Psychophysics B) 正規補間法 累積正規曲線(ogive) 心理測定関数 0.75 ogive 0.5 確率 P(Response) 1 0.25 0 0 2 4 Stimulus Magnitude 6 -2 -1 0 1 2 z値 7 Psychophysics z変換と補正 長さ "+"反応率 1.7 0.048 -1.66839 1.8 0.095 -1.30917 1.9 0.286 -0.56596 2.0 0.571 0.180016 2.1 0.810 0.876129 2.2 0.952 1.668391 2.3 1.000 NA z値 0→1/(2N) 1→1-1/(2N) N: 試行数 Psychophysics z変換と補正 長さ "+"反応率 補正反応率 z値 1.7 0.048 0.048 -1.66839 1.8 0.095 0.095 -1.30917 1.9 0.286 0.286 -0.56596 2.0 0.571 0.571 0.180016 2.1 0.810 0.810 0.876129 2.2 0.952 0.952 1.668391 2.3 1.000 0.976 1.981 8 Psychophysics z変換と補正 Normal interpolation 2.0 Z[P(+)] 1.0 0.0 -1.0 -2.0 1.7 1.8 1.9 2.0 2.1 2.2 2.3 Line length (relative) z[P(+) = 0.5] = 0.0 Z = −12.937 + 6.5517 × L L(Z = 0) = 12.937 / 6.5517 = 1.97 Psychophysics C) 関数の当てはめ ロジスティック関数 (logistic function) P= 1 1 + exp(− a( x − x0 )) Logistic function 1 a = 12.275, x0 = 1.9764 P(+) 0.75 0.5 0.25 0 1.7 1.8 1.9 2.0 2.1 2.2 2.3 Line length (relative) 9 Psychophysics 1-up 1-down 刺激強度 Yes (+) 次試行の強度をdown No (+) 次試行の強度をup (閾値) 1 2 3 4 5 6 7 8 9 10 試行 reversal(反転) Psychophysics 1-up 1-down:例 法 11.0 10.0 音強度(dB) 9.0 8.0 7.0 6.0 5.0 4.0 0 5 10 15 20 25 30 35 試行 10 Psychophysics 変形上下法 transformed up-down method 1-up 2-down P(No) = P(Yes)2 = 0.5 P(Yes) = 0.707 Psychophysics 1-up 2-down 連続2回の 刺激強度 Yes (×) 次試行の強度をdown No (×) 次試行の強度をup 閾値 1 2 3 4 5 6 7 8 9 10 試行 11 Psychophysics 1-up 2-down:例 上下法 法 11.0 10.0 音強度(dB) 9.0 8.0 Yes 7.0 No 50%閾値 71%閾値 6.0 5.0 4.0 0 5 10 15 20 25 30 35 30 35 試行 Psychophysics 二重上下法 系列変 法 11.0 10.0 音強度(dB) 9.0 8.0 7.0 下降系列 上昇系列 6.0 5.0 4.0 0 5 10 15 20 25 試行 12 Psychophysics フォン尺度 人工環境デザインハンドブック, 2007, p.109, 図4.22 Psychophysics ソーン尺度 L = kI0.3 k:定数 Coren, Ward, & Enns, 1994, p.233, Figure 7-10 大串, 1987, p.101, 図10.5 13 Psychophysics Weberの法則 ∆I I I Falmagne, 1986, p.1-32, Figure 1.14 Psychophysics ∆I =k I Weberの法則 ∆Ψ = c Fechnerの仮定 Ψn = Ψn −1 + c log I n = log I n −1 + log k ′ Ψ= c × log I (Fechnerの法則) log k ′ 14 Psychophysics 8 7 6 ∆Ψ = c = 1 Ψn = Ψn −1 + 1 感覚量 5 4 3 2 Ψ0 1 0 0 1 2 3 4 5 6 7 8 9 1011121314151617 I0 刺激量 I n = (k + 1)× I n −1 = 2 × I n −1 ∆I = k =1 I Psychophysics 14 Ψ = 1.0 + 1.4427 × log I 12 感覚量 10 8 6 4 2 0 0 50 100 150 200 250 300 刺激量 15 Psychophysics 14 1 × log I log 2 = 1.0 + 1.4427 × log I 12 Ψ = 1 .0 + Ψn = Ψn −1 + 1 感覚量 10 8 6 4 1 2 0 log(2) 0 1 2 3 4 5 6 log(刺激量) I n = (k + 1)× I n −1 = 2 × I n −1 log I n = log 2 + log I n −1 16
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