研究方法與實例簡介 中山醫學大學 心理系 何明洲 如要採用，請告知作者，並註明出處

大綱 1. 實驗設計簡介 1.Within-subject design 1.Single factor 2.Multiple factors 2.Between-subject design 3.Mixed design 2. 論文實例介紹

研究之初  研究問題的建立與改變  同一個研究問題細分成許多不同的研究方向 來檢驗此問題  不同的研究方向延伸出其他的研究問題  匯集而成的研究成果，逐漸建立理論  再由理論延伸出相關問題

實驗設計簡介

Within-Subject Design  Also called repeated-measures design  Experiment time is usually brief (< 30 minutes)  Good when the population of interest is scarce 例如： betel nut chewer

Within-Subject Design  No need to worry about equivalent group problem  Statistically, remove the variance due to the individual difference from the nonsystematic error, increasing the probability to reject null hypothesis

Treatment Subject123Mean Mean SS between subj NO difference between treatments due to subject difference ∵ within-treatment errors include between-subject difference

Counterbalance Testing once per condition Complete counterbalance 2 conditions: 2!=2 orders (at least 2 participants), [1,2] [2,1] 3 conditions : 3!=6 orders (at least 6 participants), [1,2,3] [1,3,2] [2,1,3] [2,3,1] [3,1,2] [3,2,1] 4 conditions : 4!=24 orders (at least 24 participants) 10 conditions : 10!= orders GOOD for fewer conditions

Counterbalance

Many conditions (e.g., > 3): Use partial counterbalancing Latin squares ： 1.each condition appears once in each raw and column; 2. Each condition precedes and follows each condition one time

Block randomization Block randomization ：當每一種情境出現的次 數超過一次時，可使用此法 In each block ， condition orders are randomized 3 conditions (A, B, C)

A-C-B Block 1 Block 2 A x 3 B x 3 C x 3 A x 3 B x 3 C x 3 Block 1 Block 2 C-B-A

Block randomization  情緒刺激（雙字詞或臉） x 情緒種類（中性、 恐懼或高興） x 5 repetitions (trials)  6 (2x3) conditions, each repeats 5 times  共 2 x 3 x 5 = 30 trials  分兩個 block 進行，一個 block 有 30 trials 。故 實驗共有 60 trials (30 trials x 2 blocks)

A x 5 B x 5 C x 5 D x 5 E x 5 F x 5 A x 5 B x 5 C x 5 D x 5 E x 5 F x 5 Block 1 Block 2 臉詞 中性 AD 恐懼 BE 高興 CF

Block randomization  可和 counterbalancing 搭配  情緒刺激（雙字詞或臉） x 情緒種類（中性、 恐懼或高興） x 5 repetitions (trials)  First block: 雙字詞（ 15 trials = 3 x 5 ）  Second block: 臉（ 15 trials = 3 x 5 ）  complete counterbalance  [1,2] [2,1]  看實驗結果來判斷是否和 counterbalancing 搭 配

A x 5 B x 5 C x 5 A x 5 B x 5 C x 5 Block 1 Block 2 臉 詞 A x 5 B x 5 C x 5 A x 5 B x 5 C x 5 Block 1 Block 2 臉 詞

Within-Subjects, Single factor

 2 levels Lee and Aronson (1974), how do we maintain balance in a moving environment IV: moving direction of wall and ceiling (backward or forward) Student’s t test  ≥ 2 levels Steele, Ball, and Runk (1997), examine the Mozart effect IV: Listening music (control, Mozart, and soothing environment sounds)

Analyzing Single-Factor, >2 levels F Test (analysis of variance, ANOVA 變異數分 析 ) ≥ 2 conditions (or groups) When 2 conditions, F = t 2 When more than 2 conditions, why not use t test?

EXAMPLE: F Test 用 t test 作多重比較, 至少出現一個 type I error 機率 1 – (1 – alpha) c (C: # of paired comparisons)  噪音程度 ( 無, 低, 中, 高 ) 對記憶的影響 C = 4!/(2!2!) = 6 1-(1-.05) 6 =.26 (=26%!!!)  F test 同時比較多組, alpha 控制在.05 H 0 : μ 1 = μ 2 = μ 3 = μ 4 …

EXAMPLE: F Test  Omnibus F test H 0 : μ 1 = μ 2 = μ 3 = μ 4 …  Post hoc comparisons Paired comparisons Control “overall” alpha at.05 Many control methods: Bonferroni, Shaffer, Sheffet and so on

Within-Subjects, multiple factors

FACTORIAL DESIGNS Factorial Designs : Designs with more than one independent variable (or factor) 噪音（高 vs. 低）影響雙字詞記憶 噪音（高 vs. 低） x 詞頻（高 vs. 低）

Presentation rate 2-sec4-sec Type of training Imagery Rote Factorial matrix

Factor B B1B2 Factor AA1A1B1A1B2 A2A2B1A2B2 Factorial matrix

FACTORIAL DESIGNS Simplest Factorial Design 2 x 2 (two-by-two) factorial design Has two independent variables, each IV has 2 levels 4 conditions Number of levels of first IV x Number of levels of second IV x Number of levels of third IV…

FACTORIAL DESIGNS Interpretation of Factorial Designs (A x B) Main effects of an independent variable ： effect of A factor ONLY (regardless of B factor, average out B factor) Interaction between the independent variables (how does effect of A factor vary with B factor?) ，條件 機率 A (A1, A2) x B (B1, B2) 使用圖表讓讀者瞭解

詞頻 高低 噪音程度高 A1B1A1B2A1 低 A2B1A2B2A2 B1B2

詞頻 高低 噪音程度 高 AB 低 CD A - B = C – D 詞頻的效果是否隨者噪音程度改變 A – C = B – D 噪音效果是否隨者詞頻程度改變

FACTORIAL DESIGNS

 NOTE: Once you obtain both main and interaction effects, interpret the interaction in higher priority

論文實例介紹

常見名詞解釋  SOA (Stimuli Onset Asynchrony)  ISI (Inter-Stimuli Interval)  Visual angle  Viewing distance 視角  公分  畫素

Time On Off S1S2 SOA (stimulus onset asynchrony) ISI (inter-stimuli interval)

Fig. 8-26, p. 181 論文通常都給 viewing distance 與 visual angle ，要自 行轉成公分和畫素

視角  公分

公分  視角

公分  畫素  dpi (dot per inch): 每英 吋所呈現的列印點數 右鍵內容  設定值  進 階

公分  畫素  螢幕解析度 : 640x480 、 800x600 、 1024x768 … 等， 解析度越來越好，因為螢幕單位長度中塞進了更多 的像素  螢幕尺寸  基本上 17 in 螢幕， Eprime 調 1280x1024 ，會成為約 96dpi  同一螢幕同一刺激， Eprime 解析度調越小，呈現 刺激越大  畫好後，記得用尺量，較為準確

方法結構  Participants  Apparatus  Stimuli***  Design***  Procedure***

Right hemispheric dominance in processing of unconscious negative emotion Sato and Aoki

3 x 2 factorial design

Viewing distance = 57 cm 視角  公分  畫素

Zeelenberg, Wagenmakers and Rotteveel The Impact of Emotion on Perception

3 x 3 factorial design

Effects of instantaneous object input and past experience on object-based attention Ho and Yeh

Design and procedure At the beginning of each trial, a central fixation (a plus sign) and two vertical rectangles (2° x 16°) appeared for 1000 ms (see Figure 1). These two rectangles were at the left 7° and right 7° eccentricity. Because the spatial extent of initial focusing of attention modulates the object effect (Goldsmith & Yeari, 2003), we added a pre-cue event (four Ls, 3° x 3°, surrounding the two rectangles) to expand the focus of attention that includes the two rectangles. The distance between the corner of each L and the central fixation was 14.6°. The four Ls appeared for 35 ms.

Seventy ms after the four-Ls offset, a red-colored cue (consisting of the object outline at one end of the object) was presented with 76% validity at one of the four ends of the two rectangles. The cue presentation duration was 100 ms and the target (a grey square, 2° x 2°) appeared 200 ms after cue offset. On the invalid trials, the target could appear on the uncued location occupied by the cued object (50%; invalid-same condition) or at an equidistant location on an uncued object (50%; invalid-different condition). The target remained on until observer response or 2 sec, which was recorded as an error. In addition, catch trials (20% of trials) with no target were also presented. When participants responded in the catch trials or the target detection time was less than 200 ms, a sound feedback was given.

The experiment consists of 30 practice trials and 600 formal trials (380 valid, 120 invalid, and 100 catch trials). The variable of interest was cue validity (valid, invalid-same, invalid-different). All conditions (three validity and catch trials) were randomized within trials.

練習一 幾 x 幾的 factorial design 幾個 trials 畫出刺激材料的大小

Object-based attention: Sensory modulation or priority setting? Shomstein and Yantis

練習二 請畫出刺激材料的大小