highly significantp < 0.0001
The difference between one- and two-talker conditions was highly significant for both groups ( Z = 4.87, p < 0.0001 for Boston, Z = 4.22, p < 0.0001 for Tsimane’, Wilcoxon signed-rank test); when expressed as sensitivity, Boston participants achieved a mean d -prime of 4.27, and Tsimane’ participants achieved a mean d -prime of 3.23.