function trials = buildTrainTrials(disp_struct, task_struct)

    % define each fc stimulus pair trial
    stimPairs = [1,2; 3,4;];
    
    % will hold all the trials
    fcTrials = [];
    
    % loop through each pair
    for pI = 1 : size(stimPairs, 1)
        % will hold the stimulus trials
        pairTrials = nan(task_struct.numTrainReps, task_struct.cRT);
        pairTrials(:, task_struct.cTrialCond) = task_struct.FC;
        startID = 1 + 10*(pI - 1);
        pairTrials(:, task_struct.cTrialID) = startID:(startID+task_struct.numTrainReps-1);
        
        % specs for card 1
        pairTrials(:,task_struct.cS1) = stimPairs(pI, 1);
        stim1Win = rand(task_struct.numTrainReps, 1) <= task_struct.pWin(stimPairs(pI, 1));
        pairTrials(stim1Win,task_struct.cS1Rew) = task_struct.WIN;
        pairTrials(~stim1Win,task_struct.cS1Rew) = task_struct.LOSS;
        % specs for card 2
        pairTrials(:,task_struct.cS2) = stimPairs(pI, 2);
        stim2Win = rand(task_struct.numTrainReps, 1) <= task_struct.pWin(stimPairs(pI, 2));
        pairTrials(stim2Win,task_struct.cS2Rew) = task_struct.WIN;
        pairTrials(~stim2Win,task_struct.cS2Rew) = task_struct.LOSS;
        
        % compile paired trials
        fcTrials = [fcTrials; pairTrials];
        
    end % for each stim pair
    
    % get all AB, CD pairs
    ABfc = fcTrials(fcTrials(:, task_struct.cS1) == task_struct.sCodes.Afc,:);
    CDfc = fcTrials(fcTrials(:, task_struct.cS1) == task_struct.sCodes.Cfc,:);
    
    % build matching nc trials
    ABnc = ABfc;
    ABnc(:, task_struct.cTrialCond) = task_struct.NC;
    ABnc(:, task_struct.cS1) = ABnc(:, task_struct.cS1) + task_struct.ncAdjust;
    ABnc(:, task_struct.cS2) = ABnc(:, task_struct.cS2) + task_struct.ncAdjust;
    % for CD
    CDnc = CDfc;
    CDnc(:, task_struct.cTrialCond) = task_struct.NC;
    CDnc(:, task_struct.cS1) = CDnc(:, task_struct.cS1) + task_struct.ncAdjust;
    CDnc(:, task_struct.cS2) = CDnc(:, task_struct.cS2) + task_struct.ncAdjust;
    
    % knit the fc and nc trials together
    AB = nan(2*size(ABfc,1), size(ABfc,2));
    AB(1:2:end) = ABfc;
    AB(2:2:end) = ABnc;
    % CD trials
    CD = nan(2*size(CDfc,1), size(CDfc,2));
    CD(1:2:end) = CDfc;
    CD(2:2:end) = CDnc;
    
    % now knit all AB, CD,trials toghether
    % maintaining the order within each AB, CD and EF set
    trials = nan(2*size(AB,1), size(AB,2));
    slots = reshape(randperm(size(trials,1)), size(AB,1), 2);
    % assign AB slots
    trials(sort(slots(:,1)),:) = AB;
    trials(sort(slots(:,2)),:) = CD;
    
    
    trials(:, task_struct.cTrialNum) = 1:size(trials,1);
    % stim ordering for each trial
    trials(:,task_struct.cIsS1Left) = rand(size(trials,1), 1) >= 0.5;
    trials(:,task_struct.cTrialType) = task_struct.TRAIN;
    
end % function