We conducted a behavioral study in three groups ofparticipants. All the participants performed the ANT, andtheir response times (RTs) and accuracy scores were measured. One experimental group participated in an 8-weekMBSR course that met once weekly for 3 h. All membersof this group were naive to meditation and received training in focusing attention on a single target, such as thebreath, consistent with developing concentrative attention. The other experimental group participated in a fulltime 1-month mindfulness retreat. All members of thisgroup had prior experience with concentrative meditationand received minimal group-level instructions on specificpractices in addition to instructions to focus on the outbreath. The ANT was performed immediately before thestart (Time 1) and shortly after completion of the MT program (Time 2) for both groups. Their performance wascompared with that of control participants, who were alsotested at two time points. We hypothesized that MT-relatedimprovements on ANT performance would correspond totrials that index the aspects of attention that are cultivatedand perhaps enhanced by MT