Supplemental material
Figure S1. All stimuli used in Experiments 1 and 2. Manipulable man-made objects (tools) and animals were
either elongated or non-elongated. The low-level image properties (luminance histograms and rotational average
of the Fourier spectra) were matched across all exemplars (of all categories) using the SHINE toolbox
(Willenbockel et al., 2010). Exemplar numbers are provided in the bottom left corner; numbers in red font
indicate stimulus exemplars not used in Experiment 2.
Figure S2. Stimulus elongation and orientation. (A) Elongation of stimulus exemplars expressed as width/length
ratios across different stimulus sets. In Ludwig et al. (2015), Almeida et al. (2014), and Sakuraba et al. (2012) all
elongated tool stimuli had a width/length ratio ≤ 0.4 (dotted line), while all non-elongated tool stimuli had a
width/length ratio > 0.4 (width W orthogonal to the longest extension L, see example). The tool stimuli used in
this study (Darcy, Exp.1) are identical with the tool stimuli used in Ludwig et al. (2015); the elongated and nonelongated animal stimuli used in Darcy et al. (Exp.1) show similar width/length ratios. (B) Orientation of
stimulus exemplars expressed as clockwise deviation (0-179°) from 12 o’clock (see example). Note that in Darcy
Exp.2 a subset of stimuli from Darcy Exp.1 was used.
Figure S3. Forced-choice (2AFC) discrimination performance for invisible primes in the first control experiment
across all participants included in the main analysis. A) Experiment 1 (N=23). B) Experiment 2 (N=27). Blue
circles represent participants for whom “invisibility” was defined by PAS = 1 ratings and chance-level
discrimination performance. Red circles represent participants for whom “invisibility” was defined by PAS = 1
or PAS = 2 ratings and chance-level discrimination performance.
Figure S4. Probe detection thresholds (N=7). In a probe detection task with a contrast increment probe
(Tsuchiya, Koch, Gilroy, & Blake; “Depth of interocular suppression associated with continuous flash
suppression, flash suppression, and binocular rivalry“; Journal of Vision 2006), we used Mondrian masks (left
bar), Mondrian masks with smaller rectangles (middle bar), and random noise masks (right bar). The effect of
mask type was significant (F2,12 = 10.85, p = .006). Unpublished data.
Table S1. Full results of repeated measures ANOVA for Experiment 1.
category task
Target Category (TC)
Target Elongation (TE)
Shape Congruency (SC)
Category Congruency (CC)
F1,22 =0.038, p = .848, ηp2 = .002
F1,22 =0.302, p = .588, ηp2 = .014
F1,22 =0.206, p = .654, ηp2 = .009
F1,22 =0.241, p = .629, ηp2 = .011
TCxTE
TCxSC
TExSC
TCxTExSC
TCxCC
TExCC
TCxTExCC
SCxCC
TCxSCxCC
TExSCxCC
TCxTExSCxCC
F1,22 =0.012, p = .914, ηp2 = .001
F1,22 =1.381, p = .252, ηp2 = .059
F1,22 =3.670, p = .068, ηp2 = .143
F1,22 =0.673, p = .421, ηp2 = .030
F1,22 =0.016, p = .900, ηp2 = .001
F1,22 =3.808, p = .064, ηp2 = .148
F1,22 =0.406, p = .531, ηp2 = .018
F1,22 =0.035, p = .854, ηp2 = .002
F1,22 =0.004, p = .952, ηp2 = .001
F1,22 =0.498, p = .488, ηp2 = .022
F1,22 =0.686, p = .416, ηp2 = .030
Table S2. Full results of repeated measures ANOVA for Experiment 2.
category task
Target Category (TC)
Target Elongation (TE)
Shape Congruency (SC)
Category Congruency (CC)
F1,26 =7.442, p = .011, ηp2 = .223
F1,26 =0.018, p = .894, ηp2 = .001
F1,26 =2.850, p = .103, ηp2 = .099
F1,26 =1.956, p = .174, ηp2 = .070
TCxTE
TCxSC
TExSC
TCxTExSC
TCxCC
TExCC
TCxTExCC
SCxCC
TCxSCxCC
TExSCxCC
TCxTExSCxCC
F1,26 =4.699, p = .040, ηp2 = .153
F1,26 =1.527, p = .228, ηp2 = .055
F1,26 =2.035, p = .166, ηp2 = .073
F1,26 =0.629, p = .435, ηp2 = .024
F1,26 =0.949, p = .339, ηp2 = .035
F1,26 =0.001, p = .987, ηp2 = .001
F1,26 =1.276, p = .269, ηp2 = .047
F1,26 =0.135, p = .716, ηp2 = .005
F1,26 =1.463, p = .237, ηp2 = .053
F1,26 =3.284, p = .082, ηp2 = .112
F1,26 =0.132, p = .720, ηp2 = .005
shape task
Target Category (TC)
Target Elongation (TE)
Shape Congruency (SC)
Category Congruency (CC)
F1,26 =1.775, p = .194, ηp2 = .064
F1,26 =24.480, p = .001, ηp2 = .485
F1,26 =0.450, p = .508, ηp2 = .017
F1,26 =0.512, p = .480, ηp2 = .019
TCxTE
TCxSC
TExSC
TCxTExSC
TCxCC
TExCC
TCxTExCC
SCxCC
TCxSCxCC
TExSCxCC
TCxTExSCxCC
F1,26 =18.755, p = .001, ηp2 = .419
F1,26 =0.437, p = .514, ηp2 = .017
F1,26 =1.428, p = .243, ηp2 = .052
F1,26 =5.877, p = .023, ηp2 = .184
F1,26 =0.001, p = .997, ηp2 = .001
F1,26 =1.066, p = .311, ηp2 = .039
F1,26 =0.335, p = .568, ηp2 = .013
F1,26 =5.622, p = .025, ηp2 = .178
F1,26 =0.546, p = .467, ηp2 = .021
F1,26 =0.001, p = .978, ηp2 = .001
F1,26 =0.045, p = .833, ηp2 = .002