Millisecond Forums

The <variables> element substitutes *elements* based on groups, as in

<variables>
/ group = (1 of 2) (mytext = group1text)
/ group = (2 of 2) (mytext = group2text)
</variables>

<trial mytrial>
/ stimulusframes = [1=mytext]
...
</trial>

<text group1text>
/ items = ("Group 1")
...
</text>

<text group2text>
/ items = ("Group 2")
...
</text>

Note the complete *absence* of any element called <text mytext> -- that is what is substituted via <variables>.

If you want to use <variables> in your particular case, you need to substitute entire <page> elements in the same way as demonstrated above with <text> elements.

Alternatively, you'll simply want to do:

<values>
/ redkey = ""
/ bluekey = ""
</values>

<expt>
/ onexptbegin = [values.redkey="left"; values.bluekey="right"]
/ subjects = (1 of 2)
...
</expt>

<expt>
/ onexptbegin = [values.redkey="right"; values.bluekey="left"]
/ subjects = (2 of 2)
...
</expt>

<page intro>
^Welcome to this study!
^^A red or a blue square will appear on either the left or the right side of the screen.
^^Press the *<%values.bluekey%> shift key* as quickly as possible whenever you see the
*blue square*.
^^Whenever you see the *red square*, press the *<%values.redkey%> shift key* as quickly as possible.
</page>

Thanks!
Still, it would be helpful to have a page in the manual that explains the use of variables and values. It might save you a lot of time by not having to respond to these types of questions.
I do appreciate your quick and helpful response though!

Diane

The <variables> element is documented in the language reference, however it is not indexed because it is considered (mostly) obsolete.

Is there a way to set values (in an Expt element) by group number rather than subject number?

Yes, of course. Set the <expt>s' /groupassignment attributes to 'groupnumber'.