Discussion #4:
Stanovich Chapter 10
Please write a one-page double-spaced typed discussion preparation paper addressing the following:
In chapter 10, Stanovich discusses how hard it is for people to engage in probabilistic reasoning and how this leads to misunderstandings about psychological science.
Stanovich describes an interesting mini-experiment that can be used to demonstrate your “psychic powers” to your friends. In fact, the phenomenon is due to the Gambler’s Fallacy. Read how the demonstration works on page 163. For our assignment this week, we will see if we can convince your family or friends of your psychic powers.
Here’s the set up. Find someone (a friend, family member) who is willing to participate in a 15-minute experiment for your psychology class. Tell your participant that your professor claims that our minds are more powerful than we think and that many people appear to have weak, but demonstrable psychic powers. Tell them they will write a random number, choosing from “1,” “2,” or “3,” next to each of the two hundred numbers on the attached page. Then say “I’m going to have you look at the list and try to mentally send me each number. I will try to guess the each number as you attempt to send it to me. I’ll ask you to keep track of the numbers I guess so we can check my accuracy after we’re done.”
After the participant agrees to help, you ask “what should my success rate be if I had no psychic powers and was just guessing?” Hopefully they realize it would be 33% (1 in 3 for each trial). Then ask “How much above 33% would I have to get for you to start considering that I might have psychic powers?” Encourage them to accept a reasonably low percentage, like 36% or 40%.
Then do the experiment. Print out the attached form (2 pages). Your participant writes 1, 2 or 3 next to each numbered blank (in the column labeled “1, 2 or 3”). Then starting with trial #1, the participant concentrates on the number and after a few seconds you guess 1, 2, or 3. The participant writes your guess (in the “Guess” column) and tells you what the correct number was. You do the same for trials 2 through 200. The trick is that you always guess one of the two numbers that was not the participant’s previous number. For example, if on trial #67 you guess “1,” but the participant’s number was “2,” then on trial #68 you will guess one of the numbers that is not “2” (i.e., 1 or 3). On trial #68, if the participant’s number is “3,” then you will guess something other than “3” (i.e., 1 or 2) on trial #69. Your guesses are not affected by whether you were correct or not; they are guided by what the participant’s previous number was.
After you have guessed numbers for all 200 trials, total your number of correct answers and divide by 2. This will give you your percentage correct, which is probably bigger than 33%.
Now debrief your participant. Ask if this is evidence of your psychic powers. Then reveal that there was a trick involved and see if they can figure out the trick. Describe the trick, framing it in terms of sthe Gambler’s Fallacy.
Informally (no APA format) write up the results of this mini-study, including your participant’s reactions. We’ll discuss your results in class.
Trial / 1,2 or 3 / Guess / Correct? / Trial / 1,2 or 3 / Guess / Correct?1 / 51
2 / 52
3 / 53
4 / 54
5 / 55
6 / 56
7 / 57
8 / 58
9 / 59
10 / 60
11 / 61
12 / 62
13 / 63
14 / 64
15 / 65
16 / 66
17 / 67
18 / 68
19 / 69
20 / 70
21 / 71
22 / 72
23 / 73
24 / 74
25 / 75
26 / 76
27 / 77
28 / 78
29 / 79
30 / 80
31 / 81
32 / 82
33 / 83
34 / 84
35 / 85
36 / 86
37 / 87
38 / 88
39 / 89
40 / 90
41 / 91
42 / 92
43 / 93
44 / 94
45 / 95
46 / 96
47 / 97
48 / 98
49 / 99
50 / 100
Trial / 1,2 or 3 / Guess / Correct? / Trial / 1,2 or 3 / Guess / Correct?
101 / 151
102 / 152
103 / 153
104 / 154
105 / 155
106 / 156
107 / 157
108 / 158
109 / 159
110 / 160
111 / 161
112 / 162
113 / 163
114 / 164
115 / 165
116 / 166
117 / 167
118 / 168
119 / 169
120 / 170
121 / 171
122 / 172
123 / 173
124 / 174
125 / 175
126 / 176
127 / 177
128 / 178
129 / 179
130 / 180
131 / 181
132 / 182
133 / 183
134 / 184
135 / 185
136 / 186
137 / 187
138 / 188
139 / 189
140 / 190
141 / 191
142 / 192
143 / 193
144 / 194
145 / 195
146 / 196
147 / 197
148 / 198
149 / 199
150 / 200