What is the study with the dual-task experiment that involved a colour-wheel change detection task? This may be a long-shot, but I'm looking for a paper that I vaguely remember reading a few years ago. Unfortunately I can't remember many details about the paper or its content, and thus my multiple attempts at keyword searches have failed. I'm posting this question in the hope that someone recognises the few details I do remember.

The paper presented more than one experiment, but the one I'm trying to recall involved a colour wheel/pie displayed in the centre of the screen. The slices of the pie were each a different colour and the colours would change a few times throughout each trial. There were only a small number of slices/colours. The observer's task was to count the number of times the colours changed. While doing this the observer also had to perform another task, for which the stimuli were shown on the rest of the display, in peripheral vision. I can't remember what the other task was, though it may have been a multiple object tracking task or a visual search task. The paper may have been about the effect of attentional load on working memory, though I'm not sure about that.
Your description sounds a little bit like Experiment 3 from 

Hollingworth, A., Richard, A. M., Luck, S. J. (2008) Understanding the function of visual short-term memory: Transsaccadic memory, object correspondence, and gaze correction. Journal of Experimental Psychology: General, Vol 137(1), 163-181. PDF

See Fig. 7 on page 172 for a picture of the display utilized in this experiment.