How to avoid presenting targets consecutively

[Mark A]

Dear E-Prime group,
I am fairly new to E-Prime, but thus far have found online discussions
within the group, as well as PST instructions and examples that have
allowed me to program everything required, with one exception. The
experimental task is simple: A participant listens to a series of
words and presses a button whenever a particular word is heard (i.e.,
the target word, "apple" in the example below). The target word is
presented 4 times.

My problem is this: I wish to present a series of stimuli (.wav files)
randomly, with the restriction that I do not want "Target" files to be
presented consecutively. Rather, I want them to be separated by at
least one distractor (or non-target).

To illustrate, this is an excerpt from one of my lists:

Weight	Nested	Procedure  	Sound		Talker	Target	SoundDur
1				MAppleTrial	m1apple.wav	m1		yes		422
1				MAppleTrial	f4apple.wav	f4		yes		546
1				MAppleTrial	m1apple.wav	m1		yes		422
1				MAppleTrial	f4apple.wav	f4		yes		546
1				MAppleTrial	m2bear.wav	m2		no		332
1				MAppleTrial	f3bin.wav   	f3		no		375
1				MAppleTrial	m3cat.wav	        m3		no		383
1				MAppleTrial	f2chalk.wav	f2		no		586
..... and so forth (there are 4 targets and 23 distractors).

Currently, I have the list set to "Random", however, this does not
guarantee that the Target files (top 4 rows) will not occur
consecutively. I think that the solution will involve a conditional
statement (perhaps using In line) comparing whether the previous file
presented was a target, but I am unsure how to implement this.

An additional consideration is what to do if there are only 2 cycles
left, and the two files left are both target files. If this is very
hard to avoid, I am willing to live with this, as it is unlikely to
occur very often. Any tips or links to helpful discussions on similar
topics will be very much appreciated.

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