Related concerns can also be raised for trials examining the effects of supplementing diet with σ3 fatty acids (a class of polyunsaturated fat present in, for example, oils, nuts, and fish), where small or absent effects may reflect control groups that have a relatively high consumption of these nutrients.[7] A 6-month trial with these fatty acids published in 2012[31] is no exception, which may explain the small effects reported from this trial selectively on verbal fluency, with no effects on psychomotor speed, executive functioning, and working memory.