Using two sets of the MST within 40 min of eachother

[Daniel Callow]

Hello,

I would like to look at the effects of a 30-minute exercise intervention on pattern separation in older adults. I currently plan to have participants perform the MST right before exercise and then perform a different set about 15 minutes after the exercise is complete.

I wonder if anyone has any experience running different versions of the MST on the same day in such a short time frame from each other? Are there practiced effects (from what I've read, no) and is there a lot of semantic overlap between the sets that might interfere if it is such a short time frame between tasks?

Thank you for any guidance you can provide!

Daniel Callow

[Shauna Stark]

As long as you use different sets (1-6, for example), there should be minimal interference in the items and they are matched for lure difficulty. It is worth noting that Sets 1-6 are simply reorganized sets of images from Sets C-G, so do not mix numbered and lettered sets!

We have not seen any test-retest effects, even when administered in the same session (see Stark et al., 2015; Behavioral Neuroscience).

Good luck and I'm eager to see your results!

Best,

Shauna Stark

[Daniel Callow]

Hi Shauna,

We are just about to start testing so I wanted to make sure my organization of the stimuli sets makes sense. We have participants coming in on 2 separate days. On experimental days 1 and 2 they will perform the MST phase 1 and phase 2 before and then again after a 40-minute intervention or control. In total, this means we will have 4 different testing points and thus need 4 different sets. My initial thoughts were to use sets 1-4, as I am wondering if it might be best to have a familiarization task and have the participants do either set 5 or 6 during the baseline visit. My participants will be older adults and I am a bit worried about them having trouble initially with the directions and pressing the correct keys (do you have a set script of directions of participants you think works well?). 

As for the 4 experimental sets, I will be counterbalancing the order of the day 2 and day 3 condition. How should I set up the stimulus sets? Should I have all participants perform Set 1 and then set 2 on day 2 and then set 3 and set 4 on day 3? Are the sets matched to this extent?

Thank you for your advice. We are very excited to get started!

Best,

Daniel Callow

[Shauna Stark]

Generally, we find the MST to be pretty stable, but allowing people to familiarize themselves with the buttons during baseline session wouldn't be a bad idea. We know that the results are robust to repeat testing as long as different images are used. I would counterbalance stimulus sets across all 4 or 5 of your time points. We did try to match the sets for difficulty, so you could use any/all from Sets 1-6.

We do have written instructions, in addition to the video instructions prior to test that I HIGHLY recommend using. They can both be found on our website: https://faculty.sites.uci.edu/starklab/mnemonic-similarity-task-mst/ under Downloads.

Good luck!

Shauna