On each trial, a central arrow pointed to a target image to the left or right. You task was to respond as quickly as possible whether the target image was a tool or a nontool.

There were two independent variables. The first was whether the target image was a tool or not. The second independent variable was the position of the target image (left or right of center). The dependent variable was the time between the appearance of the stimulus and your response. Trials where you reported the target type incorrectly were repeated at a random trial later in the experiment.

What do we predict participants will do? Why? The visual system is organized so that images to the left of looking straight ahead are sent to the right hemisphere and images to the right of looking straight ahead are sent to the left hemisphere. The left hemisphere is known to be specialized for processing tools (relative to the right hemisphere). So, you should respond faster to a tool target image when it is positioned on the right side of the screen. You should respond a bit slower if a tool target image is position on the left side of the screen. However, there should not be much difference for the nontool images.

You will use your data to run a Within Subjects Two-way ANOVA (Analysis of Variance) to test whether your data show an effect of hemispheric specialization. Although the test is commonly referred to as "within subjects", in this experiment there is only one subject (you). However, the test really refers to a dependency between the measures. Usually this dependency is for data gathered from a single subject, but in this experiment it refers to data from a pair of images (an image set). Each pair is shown four times and varies which image is the target (tool or nontool) and its position (left or right). Your responses to these stimuli should be related to each other, and a within subjects ANOVA can use that relationship to factor out some variance. This factorization makes the test more sensitive to the effects of image types, positions, and their interaction.

This analysis allows you to simultaneously run three related hypothesis test. The first test explores a main effect for the type of target image (tool or nontool). The null hypothesis is that the mean reaction time is the same for both image types: H0: tool = nontool; while the alternative hypothesis is that the mean reaction times are different: Ha: tool nontool.

The second hypothesis test explores the effect for the position of the target. The null hypothesis is that the mean reaction time is the same for the two positions: H0: left = right; while the alternative hypothesis is that the mean reaction times are different: Ha: left right.

Finally, you can test for an interaction of the main effects. This investigates whether there is a difference in the differences of mean reaction times. For example, if you show hemispheric specialization for tools, then there should be a difference in reaction times for tools on the right side compared to the left side, but there should be no position effect for nontools. The null hypothesis is that there is no difference in these differences: H0: tool,left - tool,right = nontool,left - nontool,right; while the alternative hypothesis is that there is a difference in the differences: Ha: tool,left - tool,right nontool,left - nontool,right,

For all the tests we will use = 0.05.

Mean RT for object type Tool, and position Left: (The difference between your answer and the correct value must be less than 0.01.) Mean RT for object type Tool, and position Right: (The difference between your answer and the correct value must be less than 0.01.) Mean RT for object type Nontool, and position Left: (The difference between your answer and the correct value must be less than 0.01.) Mean RT for object type Nontool, and position Right: (The difference between your answer and the correct value must be less than 0.01.) F-ratio for Object type (rows): (The difference between your answer and the correct value must be less than 0.01.) p-value for Object type (rows): (The difference between your answer and the correct value must be less than 0.001.) Do you reject the null hypothesis for Object type (rows)?: F-ratio for Position (columns): (The difference between your answer and the correct value must be less than 0.01.) p-value for Position (columns): (The difference between your answer and the correct value must be less than 0.001.) Do you reject the null hypothesis for Position?: F-ratio for the interaction: (The difference between your answer and the correct value must be less than 0.01.) p-value for the interaction: (The difference between your answer and the correct value must be less than 0.001.) Do you reject the null hypothesis for the interaction?:

Trial	Image set	Object type	Position	Response Time (ms)
1	18	Nontool	Left	1997
2	16	Nontool	Left	2226
3	21	Tool	Left	1739
4	8	Nontool	Left	1810
5	10	Tool	Left	1566
6	20	Nontool	Right	1962
7	6	Nontool	Left	1861
8	29	Nontool	Left	2453
9	5	Nontool	Left	2080
10	29	Tool	Left	1683
11	17	Tool	Left	1687
12	16	Nontool	Right	2022
13	19	Tool	Left	1793
14	13	Tool	Left	1702
15	23	Nontool	Right	1977
16	10	Nontool	Left	1764
17	3	Tool	Left	1671
18	15	Tool	Left	2054
19	9	Nontool	Right	2160
20	21	Tool	Right	1607
21	4	Nontool	Left	2076
22	24	Tool	Right	1620
23	25	Nontool	Left	2068
24	5	Tool	Right	1548
25	16	Tool	Right	2244
26	7	Tool	Left	1769
27	19	Nontool	Left	1991
28	1	Nontool	Left	1929
29	24	Tool	Left	1590
30	16	Tool	Left	1673
31	15	Nontool	Right	2231
32	11	Tool	Left	1718
33	26	Tool	Right	1601
34	25	Tool	Left	1685
35	1	Nontool	Right	1895
36	14	Nontool	Left	1966
37	7	Tool	Right	1722
38	17	Nontool	Right	1900
39	13	Tool	Right	1715
40	24	Nontool	Left	2021
41	12	Nontool	Right	2027
42	6	Tool	Right	1724
43	23	Tool	Right	1635
44	4	Nontool	Right	1884
45	26	Nontool	Right	1988
46	12	Nontool	Left	1527
47	17	Tool	Right	1475
48	24	Nontool	Right	1752
49	5	Nontool	Right	1749
50	28	Tool	Left	2028
51	4	Tool	Right	1693
52	1	Tool	Right	1434
53	15	Nontool	Left	2076
54	26	Nontool	Left	1979
55	28	Tool	Right	2175
56	29	Nontool	Right	1866
57	29	Tool	Right	1506
58	20	Nontool	Left	1734
59	21	Nontool	Left	2016
60	2	Tool	Left	1620
61	6	Tool	Left	1599
62	2	Nontool	Right	2092
63	26	Tool	Left	1615
64	18	Tool	Right	1847
65	3	Nontool	Right	1904
66	23	Tool	Left	1605
67	11	Nontool	Right	1820
68	2	Nontool	Left	1908
69	13	Nontool	Right	2028
70	3	Nontool	Left	1747
71	28	Nontool	Right	1795
72	9	Nontool	Left	1605
73	13	Nontool	Left	1580
74	11	Nontool	Left	2119
75	5	Tool	Left	1648
76	22	Tool	Left	1917
77	14	Nontool	Right	2455
78	4	Tool	Left	1570
79	25	Tool	Right	1420
80	6	Nontool	Right	1641
81	14	Tool	Right	1379
82	2	Tool	Right	1738
83	27	Tool	Left	1459
84	10	Tool	Right	1774
85	10	Nontool	Right	2082
86	14	Tool	Left	1345
87	7	Nontool	Right	1908
88	9	Tool	Left	1681
89	1	Tool	Left	1277
90	18	Nontool	Right	3173
91	22	Nontool	Left	1831
92	22	Tool	Right	1389
93	8	Nontool	Right	2245
94	9	Tool	Right	1439
95	20	Tool	Right	1537
96	11	Tool	Right	1458
97	25	Nontool	Right	1664
98	23	Nontool	Left	1777
99	20	Tool	Left	1305
100	3	Tool	Right	1460
101	18	Tool	Left	1451
102	7	Nontool	Left	1766
103	19	Tool	Right	1488
104	12	Tool	Right	1597
105	28	Nontool	Left	1798
106	8	Tool	Right	1882
107	22	Nontool	Right	1924
108	17	Nontool	Left	2156
109	21	Nontool	Right	2326
110	8	Tool	Left	1534
111	27	Nontool	Left	1887
112	27	Nontool	Right	1844
113	12	Tool	Left	1517
114	15	Tool	Right	1402
115	27	Tool	Right	1590
116	19	Nontool	Right	2153

All info is in the table