Millisecond Forums

Unbalanced presentation of pictures in the Dot Probe

https://forums.millisecond.com/Topic23915.aspx

By alexa - 2/25/2018

Hello there,

I have a question concercing the DotProbe. I modified the DotProbe-script (see attachment). Now I conducted a pretest with the testmonkey (10 times/"participants"). Every participant had 10 pratice trials followed by 160 „real“ trials. The real trials were as followed: 20 high-caloric pictures paired with animals/plants and 20 low-caloric pictures, also paired with animals/plants (40 DP-trials * 4 (left/right and probe/noprobe) = 160 trials). Thus every picture has to be presented 4 times. Now I have analyzed the data and I saw that some pictures are presented more than 40 times (10 participants *4), especially high-caloric pictures, but low-caloric pictures were presented less than 40 times.
The practice-block works perfectly...

I am wondering why? There has to be an error in my syntax but I don't find it.
It would be really nice if someone could help me out.
Thanks a lot,
Alexa
By Dave - 2/26/2018

alexa - Monday, February 26, 2018
Hello there,

I have a question concercing the DotProbe. I modified the DotProbe-script (see attachment). Now I conducted a pretest with the testmonkey (10 times/"participants"). Every participant had 10 pratice trials followed by 160 „real“ trials. The real trials were as followed: 20 high-caloric pictures paired with animals/plants and 20 low-caloric pictures, also paired with animals/plants (40 DP-trials * 4 (left/right and probe/noprobe) = 160 trials). Thus every picture has to be presented 4 times. Now I have analyzed the data and I saw that some pictures are presented more than 40 times (10 participants *4), especially high-caloric pictures, but low-caloric pictures were presented less than 40 times.
The practice-block works perfectly...

I am wondering why? There has to be an error in my syntax but I don't find it.
It would be really nice if someone could help me out.
Thanks a lot,
Alexa

Not seeing any obvious issue or syntax error in the script. I'm also not seeing any image selected more or less than 4 times (see attached data file from one test run, getting the exact same result in other test runs). Can you attach a raw data file that shows the imbalance?
By alexa - 2/26/2018

Dave - Monday, February 26, 2018
alexa - Monday, February 26, 2018
Hello there,

I have a question concercing the DotProbe. I modified the DotProbe-script (see attachment). Now I conducted a pretest with the testmonkey (10 times/"participants"). Every participant had 10 pratice trials followed by 160 „real“ trials. The real trials were as followed: 20 high-caloric pictures paired with animals/plants and 20 low-caloric pictures, also paired with animals/plants (40 DP-trials * 4 (left/right and probe/noprobe) = 160 trials). Thus every picture has to be presented 4 times. Now I have analyzed the data and I saw that some pictures are presented more than 40 times (10 participants *4), especially high-caloric pictures, but low-caloric pictures were presented less than 40 times.
The practice-block works perfectly...

I am wondering why? There has to be an error in my syntax but I don't find it.
It would be really nice if someone could help me out.
Thanks a lot,
Alexa

Not seeing any obvious issue or syntax error in the script. I'm also not seeing any image selected more or less than 4 times (see attached data file from one test run, getting the exact same result in other test runs). Can you attach a raw data file that shows the imbalance?
Thank you very much for you help! I have looked at your raw data and everything is a exptected... This is a little bit weird.
I just have used the testmonkey again and everything works perfectly. I am very sorry, but a possible explanation might be that I have made changes in the syntax yesterday (I remember this, see below), but didn't save it before using the testmonkey.

<blockImageDotProbeTask>
/onblockbegin = [values.task = 2]
/trials = [1-160 = noreplace(highcaloric, highcaloric, Filler)]
</block>
 to:
<block ImageDotProbeTask>
/onblockbegin = [values.task = 2]
/trials = [1-160 = noreplace(highcaloric, Filler)]
</block>

I am very sorry for the inconvenience (but reassured that everything works fine now)!
Alexa


By Dave - 2/27/2018

alexa - Tuesday, February 27, 2018
Dave - Monday, February 26, 2018
alexa - Monday, February 26, 2018
Hello there,

I have a question concercing the DotProbe. I modified the DotProbe-script (see attachment). Now I conducted a pretest with the testmonkey (10 times/"participants"). Every participant had 10 pratice trials followed by 160 „real“ trials. The real trials were as followed: 20 high-caloric pictures paired with animals/plants and 20 low-caloric pictures, also paired with animals/plants (40 DP-trials * 4 (left/right and probe/noprobe) = 160 trials). Thus every picture has to be presented 4 times. Now I have analyzed the data and I saw that some pictures are presented more than 40 times (10 participants *4), especially high-caloric pictures, but low-caloric pictures were presented less than 40 times.
The practice-block works perfectly...

I am wondering why? There has to be an error in my syntax but I don't find it.
It would be really nice if someone could help me out.
Thanks a lot,
Alexa

Not seeing any obvious issue or syntax error in the script. I'm also not seeing any image selected more or less than 4 times (see attached data file from one test run, getting the exact same result in other test runs). Can you attach a raw data file that shows the imbalance?
Thank you very much for you help! I have looked at your raw data and everything is a exptected... This is a little bit weird.
I just have used the testmonkey again and everything works perfectly. I am very sorry, but a possible explanation might be that I have made changes in the syntax yesterday (I remember this, see below), but didn't save it before using the testmonkey.

<blockImageDotProbeTask>
/onblockbegin = [values.task = 2]
/trials = [1-160 = noreplace(highcaloric, highcaloric, Filler)]
</block>
 to:
<block ImageDotProbeTask>
/onblockbegin = [values.task = 2]
/trials = [1-160 = noreplace(highcaloric, Filler)]
</block>

I am very sorry for the inconvenience (but reassured that everything works fine now)!
Alexa



Ah, yes, this makes sense.

<blockImageDotProbeTask>
/onblockbegin = [values.task = 2]
/trials = [1-160 = noreplace(highcaloric, highcaloric, Filler)]
</block>

would result in 106 to 107 "highcaloric" trials out of the 160, and the rest being "filler" trials. That would explain the imbalance you observed initially.