The participants made a minimum of 15 errors in the first phase with XAB (Phase 6).
It could be possible that the procedure of Study 1 was more effective in producing transfer of contextual functions than the procedure of Study 2 because the participants of Study 1 received more learning trials, or more reinforced trials, in the XAB phases than participants in Study 2.
The second possibility is that stimuli X1 and X2 had acquired contextual functions during the XAB teaching, but these functions did not transfer to the EF conditional discrimination.
In the XAB phases, stimulus X1 or X2 were presented without feedback.
Responding in the XAB phases, with stimulus X1 or X2 presented without feedback, indicates whether the participants acquired contextual control.
This response pattern is consistent with the assumption that contextual functions were not acquired during the XAB phases.
This performance indicates that stimuli X1 and X2 acquired functions separated from stimuli A1 and A2 during the XAB teaching.
Thus, participants received the XEF test (Phase 12, see Table 1) immediately after learning the XAB conditional discriminations (Phase 8).
In this study, only the phases with the AB and XAB conditional discriminations and the XEF test were administered.
The participants received the same procedure for learning AB and XAB as participants in Study 1, a study in which the X stimuli did acquire contextual functions.
In that study, 2 participants learned the AB and XAB conditional discriminations, as in the present study, and received trials of another, first-order conditional discrimination (CD) without feedback, until they behaved consistently.
Furthermore, in Study 2 only 2 of the 4 participants who received a procedure with all conditional discriminations, but an XAB conditional-discrimination protocol less elaborate than in Study 1, demonstrated transfer.