Sensitivity to expectancy violations in healthy aging and mild cognitive impairment.

In this study, individuals with mild cognitive impairment (MCI) were tested to see if executive dysfunction impacts their implementation of expectancy biases in a priming task. Young adults, healthy older adults, and individuals with MCI made speed-related decisions to sequentially presented word pairs. The proportion of category related (e.g., apple-fruit) versus coordinate related (apple-pear) pairs was varied to create different expectancy biases. When the proportion of category pairs was high (80%), the control groups showed an expectancy bias: Significant inhibition was observed for coordinate pairs compared with category pairs. The MCI group also demonstrated an expectancy bias but with much larger costs for unexpected targets. The findings suggest that individuals with MCI are inordinately sensitive to expectancy violations, and these findings are discussed in terms of possible executive dysfunction.