When the retro-cue was presented earlier than in Experiment 2, with a memory load of three items, or later than in Experiment 2, with a memory load of two items, there was no effect of the retro cue on d′ scores (Experiment 3a and 3b). Because the total time between study and test was held constant, the attenuation of the retro-cue effect from Experiment 1 to 3b supports the hypothesis that representations in working memory must be of sufficient memory strength to be affected by a retro-cue.