FIGURE 2.

Percent shift in F1, normalized to baseline reference of 100% (solid horizontal line) for older healthy adult participants (CTL). The top panel presents data for production of perturbed words (pear, bear care) in the unperturbed trials in baseline (Pre) and in the F1-shifted trial blocks in Ramp and Hold phases. The bottom panel presents data for production of the word “pear” in masked trials in baseline and in the masked trial blocks of the Hold and End phases. All F1-perturbations were an upward 30% F1 shift. The Ramp phase had no masked trials, the End phase included only masked trials. Error bars show standard deviation. Note that the datapoints in the Ramp are not binned into trial blocks so represent a smaller sample of data than in other phases; also that the first block of masked trials in the End phase can be treated as the final (i.e., fifth) block of masking trials in the Hold phase. Asterisks indicate significant shift in Hold and End phases relative to the baseline reference; also, in Ramp trials 21–60, 37/40 trials are significantly lower than baseline.