ERP results
One-way repeated measures ANOVA results showed that choice set size
significantly affected the amplitudes of P1 (F (3, 81) = 4.985,p = 0.003, η 2 = 0.156, Fig 2B ,3C, and 3D ). Post hoc tests revealed that when the number of
images was reduced to 4 (t (27) = 2.506, p = 0.040,d = 0.258; t (27) = 3.336, p = 0.021, d =
0.344) or 8 (t (27) = 1.947, p = 0.007, d = 0.201;t (27) = 2.777, p < 0.001, d = 0.286), the
P1 amplitudes were significantly higher than when there were 12 or 16
images . No other significant differences were observed (p s
> 0.396).
The analysis of P2 amplitudes showed that choice set size significantly
affected the amplitudes of P2 (F (3,81) = 8.676, p< 0.001, η 2 = 0.243, Fig 2B ,3C and 3D ). Post hoc tests revealed that when the number of
images was reduced to 4 (t (27) = 3.702, p = 0.002,d = 0.499; t (27) = 4.758, p < 0.001,d = 0.642) or 8 (t (27) = 2.777, p = 0.041, d= 0.375), the P2 amplitudes were significantly higher than when there
were 12 or 16 images . No other significant differences were observed
(p s > 0.396).
For the N2 component, the ANOVA results indicated that choice set size
significantly affected the amplitudes of N2 (F (3,81) = 8.466,p < 0.001, η 2 = 0.239,Fig 2B , 3A, and 3D ). Post hoc tests revealed that when
the number of images was reduced to 4 (t (27) = -2.997, p =
0.022, d = -0.412; t (27) = -4.733, p <
0.001, d = -0.651) or 8 (t (27) = -3.438, p = 0.006,d = -0.473), the N2 amplitudes were significantly higher than
when there were 12 or 16 images. No other significant differences were
observed (ps > 0.067).
As for LPC, the results suggested that choice set size significantly
affected the amplitudes of LPC (F (3,81) = 4.087, p =
0.009, η 2 = 0.131, Fig 2B, 3B, and
3D ). Post hoc tests revealed that when the number of images was reduced
to 4 (t (27) = -2.536, p = 0.013, d = -0.434) or 8
(t (27) = -3.341, p = 0.002, d = -0.572), the LPC
amplitudes were significantly higher than when there were 16 images. No
other significant differences were observed (p s >
0.058). In addition, the size of the choice set did not have a
significant effect on the amplitude of P3 (F (3,81) = 1.449,p = 0.235, Fig 2B and 3B ).