1
00:00:01,132 --> 00:00:02,897
Hi. My name's John Pierce.

2
00:00:02,897 --> 00:00:04,347
I'm a lecturer at the University of Nottingham.

3
00:00:04,347 --> 00:00:07,430
I'm the inventor of PsychoPy.

4
00:00:07,430 --> 00:00:08,648
In this demo, I'll show you how to

5
00:00:08,648 --> 00:00:09,982
create a simple experiment in PsychoPy.

6
00:00:09,982 --> 00:00:11,829
We're going to use the Stroop effect.

7
00:00:11,829 --> 00:00:14,575
When you first start up PsychoPy,

8
00:00:14,575 --> 00:00:17,293
you'll find two windows come open:

9
00:00:17,293 --> 00:00:19,907
One is the builder view, which allows you to

10
00:00:19,907 --> 00:00:22,285
construct your experiments graphically.

11
00:00:22,285 --> 00:00:25,250
And the other is the coder view, which allows you to

12
00:00:25,250 --> 00:00:27,604
create your experiments using Python scripts

13
00:00:27,604 --> 00:00:29,802
if you prefer to write code directly.

14
00:00:29,802 --> 00:00:32,864
Today we're going to be using the builder view.

15
00:00:32,864 --> 00:00:37,052
The builder view has three panels.

16
00:00:37,052 --> 00:00:41,437
It's got components. It's got one or more routines.

17
00:00:41,437 --> 00:00:43,419
Here we've got a single routine called the "trial".

18
00:00:43,419 --> 00:00:45,809
And it's got a flow which allows you to

19
00:00:45,809 --> 00:00:51,985
combine multiple routines together.

20
00:00:51,985 --> 00:00:53,780
In the case of the Stroop task, we'll need a

21
00:00:53,780 --> 00:00:56,300
a text object as part of our trial

22
00:00:56,300 --> 00:00:58,279
because we need to present a word to the subjects.

23
00:00:58,279 --> 00:01:00,521
So, let's create a text object.

24
00:01:00,521 --> 00:01:03,869
We'll call it "target". We'll have it start at

25
00:01:03,869 --> 00:01:06,107
maybe naught point five seconds,

26
00:01:06,107 --> 00:01:09,127
and it will last for five seconds.

27
00:01:09,127 --> 00:01:11,626
Notice that each of these parameters,

28
00:01:11,626 --> 00:01:14,036
as I hover my mouse over them, it gives me a tip to

29
00:01:14,036 --> 00:01:18,440
inform me about what I would be expected to include.

30
00:01:18,440 --> 00:01:21,366
There's also a help button. If I click on that,

31
00:01:21,366 --> 00:01:24,379
I'll go to the PsychoPy web site where it will tell me

32
00:01:24,379 --> 00:01:27,181
more detailed information about how to use

33
00:01:27,181 --> 00:01:29,760
this particular component.

34
00:01:29,760 --> 00:01:33,182
For now, we're not going to set color and the text

35
00:01:33,182 --> 00:01:36,763
of this text object. We'll come back to that

36
00:01:36,763 --> 00:01:39,292
later on.

37
00:01:39,292 --> 00:01:42,700
Having hit "OK", we can see the text object

38
00:01:42,700 --> 00:01:45,556
appearing in our routine and if we want to edit

39
00:01:45,556 --> 00:01:48,177
that, we can click on the icon again and we

40
00:01:48,177 --> 00:01:50,975
can get back and change our stimulus.

41
00:01:50,975 --> 00:01:53,857
Maybe we want it to be for four seconds, instead of for five.

42
00:01:53,857 --> 00:01:56,734
So it's now changed that representation.

43
00:01:56,734 --> 00:02:01,224
We also, for the Stroop task, need for the

44
00:02:01,224 --> 00:02:04,333
subjects to respond. So let's add a keyboard

45
00:02:04,333 --> 00:02:09,952
to this routine. We'll call it "response".

46
00:02:09,952 --> 00:02:13,465
We'll also start that at naught point five seconds.

47
00:02:13,465 --> 00:02:14,617
We don't want subjects to respond before

48
00:02:14,617 --> 00:02:17,176
the target was presented.

49
00:02:17,176 --> 00:02:21,162
I'm going to set this to have an infinite duration.

50
00:02:21,162 --> 00:02:24,342
If we set that to be blank, then the keyboard

51
00:02:24,342 --> 00:02:26,519
will be available forever.

52
00:02:26,519 --> 00:02:30,444
We're going to leave the allowed keys for now.

53
00:02:30,444 --> 00:02:32,394
I'll come back and change those later on,

54
00:02:32,394 --> 00:02:34,183
once we've set up our trials.

55
00:02:34,183 --> 00:02:41,268
OK, now we that the response is going to

56
00:02:41,268 --> 00:02:43,097
last forever.

57
00:02:43,097 --> 00:02:47,387
So, that's roughly what one trial is going to look like

58
00:02:47,387 --> 00:02:50,182
in the Stroop task. But we need to run more

59
00:02:50,182 --> 00:02:52,221
than one trial and right now we've got that

60
00:02:52,221 --> 00:02:54,453
routine appearing just once on our flow.

61
00:02:54,453 --> 00:02:57,761
Let's insert a loop around the trial,

62
00:02:57,761 --> 00:03:00,414
so that we can repeat it.

63
00:03:00,414 --> 00:03:02,569
If I click on "Insert loop" just once,

64
00:03:02,569 --> 00:03:05,299
and select, again with a single click,

65
00:03:05,299 --> 00:03:08,597
where we want our loop to start and stop.

66
00:03:08,597 --> 00:03:12,637
It brings up a dialog box, asking me

67
00:03:12,637 --> 00:03:14,557
what do I want to call this loop.

68
00:03:14,557 --> 00:03:16,414
We'll call it "trials". That's fine.

69
00:03:16,414 --> 00:03:21,448
Should it be random or sequential in choosing the next condition?

70
00:03:21,448 --> 00:03:22,961
Random is fine.

71
00:03:22,961 --> 00:03:25,686
We'll have five repeats, and we need to

72
00:03:25,686 --> 00:03:27,573
go and specify our conditions file.

73
00:03:27,573 --> 00:03:30,134
Now, you'll notice here it's asking for a trial

74
00:03:30,134 --> 00:03:33,963
a file that's CSV or XLSX. We need to go off

75
00:03:33,963 --> 00:03:36,485
to Excel in order to create our file.

76
00:03:36,485 --> 00:03:40,418
And click "OK". You'll see it insert the

77
00:03:40,418 --> 00:03:42,509
loop around the trial.

78
00:03:42,509 --> 00:03:45,481
Let's go and save that experiment now,

79
00:03:45,481 --> 00:03:47,937
so that we don't lose it.

80
00:03:47,937 --> 00:03:53,579
Save. I'm going to create a new folder on

81
00:03:53,579 --> 00:04:00,620
my desktop called "Stroop" and maybe I'll

82
00:04:00,620 --> 00:04:05,142
call the file "Stroop Experiment".

83
00:04:05,142 --> 00:04:09,026
Okay.

84
00:04:09,026 --> 00:04:14,455
The easiest way to define the conditions for

85
00:04:14,455 --> 00:04:18,914
your experiment is to use a spreadsheet package

86
00:04:18,914 --> 00:04:20,360
like Excel.

87
00:04:20,360 --> 00:04:22,461
We can create a number of parameters for

88
00:04:22,461 --> 00:04:25,397
our experiment, such as the word that we're

89
00:04:25,397 --> 00:04:27,803
going to present, or the color that it will

90
00:04:27,803 --> 00:04:30,862
be presented in, and we can create a number

91
00:04:30,862 --> 00:04:34,064
of different conditions. We specify one on each row.

92
00:04:34,064 --> 00:04:38,328
So, for the Stroop task, we might use the word "red"

93
00:04:38,328 --> 00:04:43,789
written in red. We might have the word "red" written

94
00:04:43,789 --> 00:04:48,140
in green. We might have the word "green"

95
00:04:48,140 --> 00:04:51,279
written in green, etc.

96
00:04:51,279 --> 00:05:04,370
"Green" in blue. "Blue" blue. "Blue" and red.

97
00:05:04,370 --> 00:05:08,024
I'm going to keep track of whether or not

98
00:05:08,024 --> 00:05:10,101
those are congruent. We don't really need to do this.

99
00:05:10,101 --> 00:05:12,668
We could always work it out later, but it's

100
00:05:12,668 --> 00:05:15,548
kind of convenient to have that stored as well.

101
00:05:15,548 --> 00:05:17,631
So, congruent and I'm going to say "1";

102
00:05:17,631 --> 00:05:20,634
that means "true"; and "0" for "false".

103
00:05:20,634 --> 00:05:25,364
That's just going to help us later on.

104
00:05:25,364 --> 00:05:28,066
Now we also need to specify what's the

105
00:05:28,066 --> 00:05:30,575
correct answer, cause PsychoPy will want to know

106
00:05:30,575 --> 00:05:33,663
whether or not the subject got it right or wrong.

107
00:05:33,663 --> 00:05:39,719
I'm going to call that "corrAns".

108
00:05:39,719 --> 00:05:43,766
These parameters can't use any punctuation

109
00:05:43,766 --> 00:05:47,543
or spaces in their names. So, I'm going to

110
00:05:47,543 --> 00:05:50,577
take away the space and give it a capital letter

111
00:05:50,577 --> 00:05:53,960
for, uh, to specify the correct answer.

112
00:05:53,960 --> 00:05:57,335
In this case, we're going to use the left,

113
00:05:57,335 --> 00:06:02,103
down, and right cursor keys from the keyboard.

114
00:06:02,103 --> 00:06:05,709
So, I'm going to specify that red -- and remember

115
00:06:05,709 --> 00:06:08,301
in the Stroop task that the subjects are asked

116
00:06:08,301 --> 00:06:10,781
to report the color of the text rather than

117
00:06:10,781 --> 00:06:14,086
the word itself. So, when the color is red, I'm

118
00:06:14,086 --> 00:06:15,898
going to ask the subjects to press "left".

119
00:06:15,898 --> 00:06:19,152
That's the left cursor key.

120
00:06:19,152 --> 00:06:20,931
When it's green they should press "down".

121
00:06:20,931 --> 00:06:23,428
"Down" again.

122
00:06:23,428 --> 00:06:26,351
When the color's blue they should press "right".

123
00:06:26,351 --> 00:06:28,294
"Right".

124
00:06:28,294 --> 00:06:31,965
And now I've got red again, so they should

125
00:06:31,965 --> 00:06:32,973
press "left".

126
00:06:32,973 --> 00:06:35,811
Okay, that defines six different conditions

127
00:06:35,811 --> 00:06:38,616
for our experiment with four different parameters.

128
00:06:38,616 --> 00:06:41,480
Okay, let's save that file.

129
00:06:41,480 --> 00:06:47,119
I'm going to put it in the same folder as my

130
00:06:47,119 --> 00:06:49,467
experiment, although you don't have to.

131
00:06:49,467 --> 00:06:52,789
And I'm going to call it "conditions.xlsx".

132
00:06:52,789 --> 00:06:54,440
It's very important that you save it

133
00:06:54,440 --> 00:06:58,250
in the XLSX format. PsychoPy can't use the old

134
00:06:58,250 --> 00:07:02,468
XLS style spreadsheets.

135
00:07:02,468 --> 00:07:07,695
Click "Save" and we're done.

136
00:07:07,695 --> 00:07:11,758
So now we need to show PsychoPy where that file

137
00:07:11,758 --> 00:07:14,364
is, and how to use it during the trials.

138
00:07:14,364 --> 00:07:18,557
The way to do that is with the loop dialog.

139
00:07:18,557 --> 00:07:21,831
So, if I just click on that loop again,

140
00:07:21,831 --> 00:07:24,559
we'll get the properties back for the loop

141
00:07:24,559 --> 00:07:27,308
and there's a conditions file. If we browse,

142
00:07:27,308 --> 00:07:31,306
we can select our file that we've just created,

143
00:07:31,306 --> 00:07:37,468
open that, and it's told me that there are

144
00:07:37,468 --> 00:07:40,055
six conditions with four different parameters.

145
00:07:40,055 --> 00:07:41,618
The parameters are color, word, congruent

146
00:07:41,618 --> 00:07:43,452
and correct answer.

147
00:07:43,452 --> 00:07:47,662
Ok? If the file had been invalid in some way,

148
00:07:47,662 --> 00:07:49,665
maybe we had a space in one of our column

149
00:07:49,665 --> 00:07:52,212
headings, then we would get a warning here to

150
00:07:52,212 --> 00:07:54,216
say that we couldn't use that file or it

151
00:07:54,216 --> 00:07:56,612
wouldn't show us the parameters were there.

152
00:07:56,612 --> 00:07:59,880
Now we can select "OK". It's showing that we've

153
00:07:59,880 --> 00:08:05,294
got five times six random trials.

154
00:08:05,294 --> 00:08:09,788
So, five different repeats of six different conditions.

155
00:08:09,788 --> 00:08:14,637
Okay, so the conditions file is now being set

156
00:08:14,637 --> 00:08:17,054
here on each repeat through the loop, we use

157
00:08:17,054 --> 00:08:18,378
a different row.

158
00:08:18,378 --> 00:08:21,315
We still need to tell the stimulus about the

159
00:08:21,315 --> 00:08:24,035
parameters that it needs to use.

160
00:08:24,035 --> 00:08:26,312
We want the color of our stimulus to be set

161
00:08:26,312 --> 00:08:31,243
by that color parameter. Now, I've typed in

162
00:08:31,243 --> 00:08:35,336
"$colour" here, spelt with a "u" because that's

163
00:08:35,336 --> 00:08:38,028
how we spelt it in the Excel file.

164
00:08:38,028 --> 00:08:42,931
And that "$" is to tell PsychoPy "This isn't a

165
00:08:42,931 --> 00:08:45,845
literal value. It's a variable."

166
00:08:45,845 --> 00:08:47,767
Okay? So, it's going to go off and find a

167
00:08:47,767 --> 00:08:50,173
variable called "colour" and see what the current

168
00:08:50,173 --> 00:08:52,200
value of that variable is.

169
00:08:52,200 --> 00:08:54,164
It's going to be red or green or blue.

170
00:08:54,164 --> 00:08:58,678
I'm also going to set that to change on every repeat

171
00:08:58,678 --> 00:09:01,493
rather than being constant.

172
00:09:01,493 --> 00:09:03,436
Okay? We don't want the stimulus just to be

173
00:09:03,436 --> 00:09:07,220
fixed to one particular color for the entire experiment.

174
00:09:07,220 --> 00:09:11,238
Similarly, the text of this text stimulus should be

175
00:09:11,238 --> 00:09:15,916
the word that we've specified in the Excel file

176
00:09:15,916 --> 00:09:19,457
and it shouldn't be "word" it should be the variable

177
00:09:19,457 --> 00:09:22,394
"word" in order to go and fetch that variable

178
00:09:22,394 --> 00:09:24,506
which is going to be red or green or blue.

179
00:09:24,506 --> 00:09:29,034
And, again, we want that to change on every repeat

180
00:09:29,034 --> 00:09:31,091
of this routine.

181
00:09:31,091 --> 00:09:40,656
Okay. We also need to set the response to be

182
00:09:40,656 --> 00:09:44,970
based on the conditions. So I need to change

183
00:09:44,970 --> 00:09:47,391
the keys that are going to be allowed for

184
00:09:47,391 --> 00:09:49,464
the subject to respond with. We don't want them

185
00:09:49,464 --> 00:09:52,128
to use the "yes" or the "no". We want them to use

186
00:09:52,128 --> 00:09:57,230
"left", "right" and "down". So, notice that any keys

187
00:09:57,230 --> 00:10:00,581
I want to put here I separate by commas and

188
00:10:00,581 --> 00:10:05,026
I have to put inverted commas around the names

189
00:10:05,026 --> 00:10:07,494
of each of the keys.

190
00:10:07,494 --> 00:10:11,775
If I leave that blank -- the entire box -- then all keys

191
00:10:11,775 --> 00:10:14,809
will be available. Okay? So that allows the subject

192
00:10:14,809 --> 00:10:19,724
to press any key. I've also got "forceEndRoutine"

193
00:10:19,724 --> 00:10:22,765
checked here. We left the response to be

194
00:10:22,765 --> 00:10:26,222
infinite but as soon as they press any key,

195
00:10:26,222 --> 00:10:28,205
it will force the end of that trial.

196
00:10:28,205 --> 00:10:30,271
So that's a useful thing for us to do.

197
00:10:30,271 --> 00:10:32,813
We're also going to want to store correct.

198
00:10:32,813 --> 00:10:36,512
So, if I check that box, we have to tell PsychoPy

199
00:10:36,512 --> 00:10:39,030
what is the correct answer on this trial,

200
00:10:39,030 --> 00:10:43,857
and if you remember, that was stored as "corrAns".

201
00:10:43,857 --> 00:10:48,495
Again, we need to use "$corrAns" to specify

202
00:10:48,495 --> 00:10:52,550
the fact that this is a variable name not,

203
00:10:52,550 --> 00:10:54,919
it shouldn't be looking for a key called "corrAns"

204
00:10:54,919 --> 00:10:56,542
cause it will never find one. It's got to use

205
00:10:56,542 --> 00:11:00,997
the variable "corrAns". And that's us done. Okay.

206
00:11:00,997 --> 00:11:06,868
Save. Okay, we're pretty much there.

207
00:11:06,868 --> 00:11:09,619
That should be a working experiment, but we do also

208
00:11:09,619 --> 00:11:12,094
want to provide the subject with some instructions.

209
00:11:12,094 --> 00:11:15,383
I'm going to insert another routine into the flow.

210
00:11:15,383 --> 00:11:20,543
When I click that button it shows me either "new"

211
00:11:20,543 --> 00:11:24,298
or "trial". Let's select "new" and I'll call it

212
00:11:24,298 --> 00:11:31,254
"instructions"... if I can spell it. "Instructions".

213
00:11:31,254 --> 00:11:35,553
It asks where I want to insert the instructions.

214
00:11:35,553 --> 00:11:38,139
We don't want it to be here because that would

215
00:11:38,139 --> 00:11:40,016
repeat the instructions on every trial.

216
00:11:40,016 --> 00:11:43,980
Let's put it before the loop. And now we can click

217
00:11:43,980 --> 00:11:48,576
on the instructions routine and we can edit that.

218
00:11:48,576 --> 00:11:52,340
So, we're going to want another text object.

219
00:11:52,340 --> 00:12:02,253
We're going to call that, say, "instrText",

220
00:12:02,253 --> 00:12:05,829
start at time zero. Duration, we'll make it infinite.

221
00:12:05,829 --> 00:12:11,737
Color white, that's fine. And we'll give it the text

222
00:12:11,737 --> 00:12:27,509
"Remember choose the color of the letters,

223
00:12:27,509 --> 00:12:33,696
ignoring the word:

224
00:12:33,696 --> 00:12:46,957
left = red, down = green, right = blue.

225
00:12:46,957 --> 00:12:49,035
Okay.

226
00:12:49,035 --> 00:12:54,680
Now because we've made that text last forever,

227
00:12:54,680 --> 00:12:56,465
we gave it an infinite duration, we need to make

228
00:12:56,465 --> 00:12:59,016
sure that the subject can get rid of them.

229
00:12:59,016 --> 00:13:05,412
So, we'll click on a keyboard, we'll allow any key,

230
00:13:05,412 --> 00:13:10,151
we'll force the end of the routine, and we won't

231
00:13:10,151 --> 00:13:12,890
bother storing anything.

232
00:13:12,890 --> 00:13:15,799
We make that last forever.

233
00:13:15,799 --> 00:13:18,192
Okay.

234
00:13:18,192 --> 00:13:23,540
If you do get that wrong, you should always be able

235
00:13:23,540 --> 00:13:25,855
to hit "escape" and you will still be able to quit

236
00:13:25,855 --> 00:13:27,442
the experiment without having to

237
00:13:27,442 --> 00:13:28,735
restart your computer.

238
00:13:28,735 --> 00:13:31,079
Okay, I'm going to save that again.

239
00:13:31,079 --> 00:13:32,589
I think we're done.

240
00:13:32,589 --> 00:13:37,067
Okay, let's just have a quick look at the

241
00:13:37,067 --> 00:13:39,364
Experiment Settings dialog box.

242
00:13:39,364 --> 00:13:42,300
In this dialog, you can control things like whether

243
00:13:42,300 --> 00:13:45,123
or not the mouse is visible during the experiment,

244
00:13:45,123 --> 00:13:48,133
the color of the background of the screen,

245
00:13:48,133 --> 00:13:51,420
whether or not it's in a window or in full screen,

246
00:13:51,420 --> 00:13:54,463
is it "screen 1" or "screen 2" if you've got

247
00:13:54,463 --> 00:13:57,029
multiple monitors, and what sort of data files

248
00:13:57,029 --> 00:13:59,560
you want to save out. So, lots of useful things there

249
00:13:59,560 --> 00:14:01,869
to control your experiment.

250
00:14:01,869 --> 00:14:05,355
Now, at this point we could construct a script.

251
00:14:05,355 --> 00:14:08,771
That'll allow you to go off and maybe learn a little

252
00:14:08,771 --> 00:14:15,104
bit about how Python works. It's about 220 lines

253
00:14:15,104 --> 00:14:18,279
long, this particular experiment. So, not too

254
00:14:18,279 --> 00:14:21,785
complicated a script. But we don't need to.

255
00:14:21,785 --> 00:14:24,826
We could actually go off and run our experiment

256
00:14:24,826 --> 00:14:26,926
by hitting the green man.

257
00:14:26,926 --> 00:14:31,149
Often takes a few seconds, especially the first time

258
00:14:31,149 --> 00:14:34,740
you run. So, be patient with that one.

259
00:14:34,740 --> 00:14:36,785
There we go. We've got a dialog box come up

260
00:14:36,785 --> 00:14:39,596
asking for the participant and the session number.

261
00:14:39,596 --> 00:14:42,103
That was also being controlled in the Experiment

262
00:14:42,103 --> 00:14:43,712
Settings dialog.

263
00:14:43,712 --> 00:14:45,359
I'm not actually going to run the experiment.

264
00:14:45,359 --> 00:14:47,964
I'll leave that to you.

265
00:14:47,964 --> 00:14:49,795
Okay. Have you found that useful?

266
00:14:49,795 --> 00:14:51,821
Check out the Demos menu for more ideas

267
00:14:51,821 --> 00:14:54,000
and I hope you enjoy using PsychoPy!