What methods did we employ in this experiment? On each trial, you saw a word in a font of a certain color. Your task was to, as quickly as possible, identify the color of the font. Although it is not necessary to read the word, it turns out that the properties of the word influence how quickly you can respond to the font color. In this case, some words were negative emotional words (e.g., angry, coffin, rage), while other words were neutral (e.g., table, kettle, seat).

The independent variable in this experiment was the emotional status of the word. The dependent variable was the response time between the appearance of the stimulus and your response. Only trials in which you made the correct classification were kept. If a trial was incorrect, it was repeated later in the experiment.

What do we predict participants will do? Why? The emotional Stroop effect is that people are usually slower to respond to the color of negative emotional words than neutral words. A common explanation is that people cannot help but read and partly process an emotional word. This automatic processing uses resources that could otherwise have been working on the color-naming task. Neutral words are not as fully processed automatically and so they provide less interference on the color-naming task.

How robust is this effect? Are there limits to this effect? The effect is quite robust and has been studied in many different situations. (There is some debate about the explanation of the effect, as some variations of this type of experiment do not fit what would be expected.) In the statistical analysis of this data, you are asked to run a one-tailed, two-sample t-test to determine if your data have a significant difference between the response times for emotional and neutral words.

The null hypothesis is that the mean reaction time for emotion words is the same as the mean reaction time for neutral words: H0: emotion - neutral = 0, while the alternative hypothesis is that the mean reaction time for emotion words is longer than the mean reaction time for neutral words: Ha: emotion - neutral > 0. We will use = 0.05. Since the number of trials is equal in each sample, you can assume homogeneity of variance.

Formulas To calculate the t test statistic, you need to first calculate the mean and variance of scores for each condition. This is done in the first four questions. Next, you need to pool the variances using the following formula

s2=(n11)s21+(n21)s22n1+n22, where n1 and n2 are the sample sizes (number of trials) for the emotional and neutral word conditions. s21 and s22 are the variances for the emotional and neutral word conditions.

The pooled variance is used to calculate the standard error of the difference of means

sX1X2=s2(1n1+1n2). Now compute the t test statistic

t=X1X2sX1X2, which has degrees of freedom df=n1 + n2 -2.

Mean reaction time for emotional words: (The difference between your answer and the correct value must be less than 0.01.) Variance of the reaction time for emotional words: (The difference between your answer and the correct value must be less than 0.01.) Mean reaction time for neutral words: (The difference between your answer and the correct value must be less than 0.01.) Variance of the reaction time for neutral words: (The difference between your answer and the correct value must be less than 0.01.) Pooled variance: (The difference between your answer and the correct value must be less than 0.01.) Standard error of the difference of means: (The difference between your answer and the correct value must be less than 0.01.) t test statistic: (The difference between your answer and the correct value must be less than 0.01.) degrees of freedom: (Your answer must exactly equal the correct value.) p-value for a one-tailed test: (The difference between your answer and the correct value must be less than 0.001.) Do you reject the null hypothesis?:

Trial	Type of word	Font color	Word stimulus	Reaction time (ms)
1	Emotional	Blue	terrorist	1808
2	Neutral	Red	table	1328
3	Neutral	Blue	cabinet	982
4	Emotional	Red	anger	950
5	Neutral	Green	hairpin	1047
6	Neutral	Blue	pencil	1406
7	Neutral	Red	curtains	1064
8	Emotional	Green	coffin	1029
9	Emotional	Red	hatred	1903
10	Neutral	Blue	item	1501
11	Neutral	Green	stove	1143
12	Neutral	Blue	mantel	1312
13	Emotional	Red	unfaithful	1051
14	Neutral	Red	metal	1023
15	Neutral	Red	square	1125
16	Emotional	Blue	sad	1069
17	Emotional	Green	abuse	1064
18	Neutral	Green	theory	1043
19	Neutral	Blue	cord	1217
20	Neutral	Red	seat	1521
21	Emotional	Red	drown	1002
22	Neutral	Red	stool	980
23	Neutral	Green	clock	900
24	Emotional	Green	lonely	911
25	Neutral	Blue	trunk	1461
26	Emotional	Red	rejected	2334
27	Neutral	Blue	ankle	1331
28	Neutral	Red	iron	1037
29	Emotional	Green	fearful	931
30	Emotional	Green	killer	873
31	Neutral	Green	stiff	869
32	Emotional	Green	depression	873
33	Emotional	Blue	death	1178
34	Emotional	Red	cruel	865
35	Neutral	Red	fabric	884
36	Emotional	Green	depressed	893
37	Neutral	Blue	contents	1420
38	Neutral	Blue	tower	1073
39	Neutral	Blue	kettle	977
40	Neutral	Blue	quart	831
41	Emotional	Blue	torture	845
42	Emotional	Red	traitor	2442
43	Neutral	Green	dustpan	1647
44	Neutral	Green	bench	1003
45	Neutral	Blue	context	1357
46	Emotional	Red	funeral	1339
47	Emotional	Blue	betray	1123
48	Emotional	Blue	murderer	1263
49	Emotional	Red	assault	1093
50	Emotional	Red	terrified	1309
51	Emotional	Blue	weapon	2076
52	Neutral	Red	elbow	956
53	Emotional	Blue	enraged	1260
54	Neutral	Red	chin	1089
55	Emotional	Red	rape	850
56	Emotional	Blue	afraid	958
57	Neutral	Green	vanity	1086
58	Emotional	Blue	rage	1265
59	Neutral	Green	part	1033
60	Emotional	Green	misery	1353
61	Emotional	Green	suffocate	872
62	Neutral	Green	method	807
63	Emotional	Green	burial	710
64	Neutral	Green	chair	748
65	Neutral	Red	lamp	1748
66	Neutral	Red	column	817
67	Emotional	Green	mad	2960
68	Emotional	Red	avalanche	1198
69	Emotional	Blue	scared	999
70	Emotional	Green	cemetery	970
71	Emotional	Blue	slave	1255
72	Neutral	Green	month	1264
73	Emotional	Red	tragedy	855
74	Emotional	Blue	suicide	1496
75	Neutral	Red	plain	910
76	Emotional	Green	angry	1267
77	Neutral	Blue	patent	1291
78	Neutral	Green	barrel	1027