Results of the mixed-effects analyses for the fixed effects.

For each effect, the coefficient’s estimates are accompanied by 95% confidence intervals in parentheses and corresponding t-values are displayed on the next line. First colum (1) is for the model with the optimal random structure and all the fixed effects. Second column (2) is for the final model, i.e. the same as in the first column but without interaction terms. Reference levels for the analyses are condition 1 (gaze-controlled aid) and mean rank of trials. “:” stands for interaction.