Hopefully it is not too late to answer your question. Randperm generates a vector of random permutation (1, 2, ... n) without duplication. In your case, 7, 12, 17, 22, … indicate “word5” - so if randperm generates a vector such as 12, 7, 22 ...., then the script should display the same words (word5) repeatedly, and that is why you saw the same stimuli on successive trials.
Here is a solution:
Assume you have a stimulus file like this:
-----
practice1
practice 2
word1
word2
word3
word4
word5
-----
and use this code to generate stim sequence
% parameters – change these parameters as you wish
n_word=5; % five words
repeatTime=12; % you wish to present each word for 12 times
n_testTrial=2; % 2 words for practice trials
combinations=perms([1:n_word]);
sequence_testing=[]
for idx_repeat=1:repeatTime
if idx_repeat>1
sequence_testing=[sequence_testing; combinations(round(rand*((n_word-1)*repeatTime)), :)'];
else
sequence_testing=[sequence_testing; combinations(round(rand*(n_word*repeatTime)), :)'];
end
tmp_lastNum=sequence_testing(end);
end
TrialIndex=sequence_testing+n_practiceTrial; % shift for practice words
'TrialIndex' can be used for stimulus presentation.
Hope this helps!
