change of reinforcement contingencies across participants

[De Brito, Stephane]

Dear E-prime experts,

 

I am working on a task in which the participant is presented with pairs
of picture on the screen. I have 10 different pictures and each picture
is associated with a reinforcement value which stays the same throughout
the experiment (e.g. the cup  always wins you 900 points and the cow
always looses you 900 points). On each trial, the participant has to
choose one of the two pictures presented (press 'q' for left hand side
picture and 'p' for right hand side picture) and win has many points has
he can. The reinforcement values are +900 +700 +500 +300 +100 -100 +300
+500 +700 +900. Sometimes the participant is presented with 2 pictures
associated with punishment (pun-pun trials) and has to choose the one
associated with the lowest punishment (i.e. scored as correct); on
pun-rew trials the rew is scored as correct and on rew-rew trials the
pictures with highest reinforcement value is scored as correct. 

 

The task is running fine, but I would like to change across participants
the reinforcement contingency for each picture so that, for example, not
every participant wins 900 point when they choose the cup. At the
moment, I have the following attributes in my listobject:

 

Picture1

Picture2

Slidestate

CorrectAnswer

Correct

Incorrect

cup.bmp

cow.bmp

1

q

You have won 900 points

You have lost 900 points

car.bmp

spoon.bmp

3

q

You have lost 300 points

You have lost 500 points

Etc...

 

Basically, I would like to keep the pairing for my attributes 'Correct'
and 'Incorrect' the same, but I want to change across participants the
pairing in my 'Picture 1' and 'Picture 2' attributes. I hope I made
myself clear. From the e-prime manual and discussion with colleagues, it
seems that the best way to do this would be with an 'array', but I have
not managed to work it out yet.  Any idea on how to achieve this would
be greatly appreciated. Many thanks.

 

Best wishes,

Stephane 

 

------------------------------------------

Stephane De Brito, PhD student

Institute of Psychiatry

King's College London

Forensic Mental Health Science Department 

Box P023 

De Crespigny Park 

Denmark Hill 

London SE5 8AF

United Kingdom

Tel: + 44 (0) 20 7848 0711

Fax: + 44 (0) 20 7848 0754

website: www.iop.kcl.ac.uk

 

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