Peter, it's better to start with a simple model first and see if it works, especially in this case with minimum amount of data.

> We model monkey to account for differences (and to see if there is an outlier); but the
> flip-side if this is that this factor hopefully "soaks up" variance attributable to monkey.

When "monkey" is not directly specified in the model as a fixed- or random-effects factor, it does not mean that the variability among the monkeys is not accounted for. Instead the variability is explained in the residuals. Directly modeling it as a fixed-effects factor requires more model parameters, leading to unstable estimation in the process, and you don't have enough data to play with.

> -ranEff '~1+Monk|Subj'

Just try

-ranEff '~1' \

and you should feel blessed if you get something interesting in the end.

Gang



Edited 1 time(s). Last edit at 12/21/2016 10:08AM by Gang.