StimTracker Artifact- detailed🔗

Effects of Artifact on ERP Derivatives by Task🔗

To assess the artifact’s impact on EEG derivatives, ERPs were computed for each task and ROI. Because there were many more artifact-free files, 100 artifact-present and 100 artifact-free files per task were randomly selected for comparison to balance the groups. Waveforms for each ERP are shown below, and differences by task and ROI are summarized in accompanying tables.

See: VEP, MMN, and Faces.

VEP🔗

Measure	N1 (40-79 ms) Mean Difference	N1 (40-79 ms) Significance	P1 (80-140 ms) Mean Difference	P1 (80-140 ms) Significance	N2 (141-300 ms) Mean Difference	N2 (141-300 ms) Significance
Mean Amplitude	Δ = 0.07 µV	p = 0.91	Δ = 0.18 µV	p = 0.77	Δ = -0.008 µV	p= 0.99
Peak Amplitude	Δ = -0.43 µV	p= 0.55	Δ = 0.67 µV	p= 0.37	Δ = -0.56 µV	p = 0.49
Peak Latency	Δ = -0.3 ms	p = 0.85	Δ = 0.1 ms	p = 0.98	Δ = -1.3 ms	p = 0.86
Table 1. Differences in ERPs between the artifact containing (n=100) and artifact-free (n=100) files. Mean differences for mean amplitude, peak amplitude, and peak latency for the Oz cluster are presented for our time windows of interest.

MMN🔗

Condition	ROI	Mean Amp Artifact (uV)	Mean Amp No Artifact (uV)	Delta (uV)	p Value	p Value Adj. (FDR)
Standard	FCz	1.25	1.264	-0.014	0.946	0.946
Standard	T7T8	1.482	0.921	0.562	0.013	0.039
Predeviant	FCz	1.349	1.437	-0.089	0.77	0.946
Predeviant	T7T8	1.279	0.641	0.637	0.055	0.11
Deviant	FCz	1.478	1.444	0.034	0.927	0.946
Deviant	T7T8	3.118	1.987	1.132	0.004	0.024
Table 2. Differences between the artifact containing (n=100) and artifact-free (n = 100) files for the mean amplitude for each condition, ROI, and time window.

Note: Differences between means are presented for each artifact designation, as well as the difference between them (delta). P-values were calculated for the differences between means, and then FDR corrected. Original and corrected p-values are presented.

Contrast	ROI	Mean Amp Artifact (uV)	Mean Amp No Artifact (uV)	Delta (uV)	p Value
Deviant-Predeviant	FCz	0.24	-0.10	0.34	0.45
Deviant-Predeviant	T7T8	1.70	1.03	0.67	0.10
Table 3. Differences in mean amplitude for the difference wave of files containing the artifact (n = 100) and artifact-free files (n = 100). Contrast

FACE Task (by ROI)🔗

Condition	ROI	Time Window (ms)	Mean Amp Artifact (uV)	Mean Amp No Artifact (uV)	Delta (uV)	p Value	p value Adjusted (FDR)
Upright (Inv)	FCz	300-600	-1.141	-1.855	0.713	0.228	0.547
Upright (Inv)	Oz	200-350	-1.38	-0.922	-0.459	0.668	0.836
Upright (Inv)	P7	200-350	1.418	1.445	-0.028	0.971	0.971
Upright (Inv)	P7	350-600	4.865	5.588	-0.723	0.496	0.744
Upright (Inv)	P8	200-350	1.933	1.705	0.229	0.789	0.836
Upright (Inv)	P8	350-600	5.144	4.862	0.282	0.799	0.836
Inverted	FCz	300-600	-1.353	-2.074	0.72	0.18	0.54
Inverted	Oz	200-350	-0.771	0.181	-0.953	0.373	0.639
Inverted	P7	200-350	1.648	3.367	-1.719	0.03	0.18
Inverted	P7	350-600	4.525	7.553	-3.029	0.009	0.108
Inverted	P8	200-350	2.728	2.958	-0.23	0.801	0.836
Inverted	P8	350-600	6.242	6.597	-0.355	0.776	0.836
Upright (Obj)	FCz	300-600	-2.185	-2.342	0.157	0.776	0.836
Upright (Obj)	Oz	200-350	0.554	1.836	-1.281	0.274	0.583
Upright (Obj)	P7	200-350	2.002	2.879	-0.877	0.316	0.583
Upright (Obj)	P7	350-600	4.968	6.708	-1.74	0.166	0.54
Upright (Obj)	P8	200-350	2.626	3.6	-0.974	0.305	0.583
Upright (Obj)	P8	350-600	5.74	7.277	-1.537	0.216	0.547
Object	FCz	300-600	-1.335	-2.302	0.968	0.09	0.36
Object	Oz	200-350	-2.097	-0.179	-1.918	0.057	0.274
Object	P7	200-350	0.607	2.357	-1.75	0.016	0.128
Object	P7	350-600	4.001	6.964	-2.963	0.004	0.096
Object	P8	200-350	1.532	1.866	-0.334	0.692	0.836
Object	P8	350-600	5.32	6.283	-0.963	0.405	0.648
Table 4. Differences between the artifact containing (n=100) and artifact-free (n = 100) files for the mean amplitude for each condition, ROI, and time window.

Note: The FACE task has 2 blocks: one with upright and inverted faces and the other with upright faces and Sheinbug objects. The upright condition is separated into its corresponding block; “Upright (Inv)” are those upright faces during the inverted block while “Upright (Obj)” corresponds to upright faces during the object block. Differences between means are presented for each artifact designation, as well as the difference between them (delta). P-values were calculated for the differences between means, and then FDR corrected. Original and corrected p-values are presented.

Contrast	ROI	Time Window (ms)	Mean Artifact	Mean No Artifact	Delta Δ	p Value	p value Adjusted (FDR)
Upright-Inverted	FCz	300-600	0.21	0.22	-0.01	0.99	0.992
Upright-Object	FCz	300-600	0.85	0.04	0.8	0.21	0.703
Upright-Inverted	Oz	200-350	-0.61	-1.1	0.49	0.64	0.703
Upright-Object	Oz	200-350	-2.65	-2.02	-0.64	0.57	0.703
Upright-Inverted	P7	200-350	-0.23	-1.92	1.69	0.05	0.703
Upright-Inverted	P7	350-600	0.34	-1.97	2.3	0.03	0.319
Upright-Object	P7	200-350	-1.4	-0.52	-0.87	0.38	0.319
Upright-Object	P7	350-600	-0.97	0.26	-1.22	0.29	0.703
Upright-Inverted	P8	200-350	-0.8	-1.25	0.46	0.61	0.703
Upright-Inverted	P8	350-600	-1.1	-1.73	0.64	0.54	0.703
Upright-Object	P8	200-350	-1.09	-1.73	0.64	0.5	0.703
Upright-Object	P8	350-600	-0.42	-0.99	0.57	0.59	0.703
Table 5. Differences between the artifact containing (n=100) and artifact-free (n = 100) files for the mean amplitude of the difference wave.

Note: These are calculated for each Region of Interest (ROI) and timewindow. The upright conditions are from the corresponding block. Differences between means are presented for each artifact designation, as well as the difference between them (delta). P-values were calculated for the differences between means, and then FDR corrected. Original and corrected p-values are presented.