Two experiments compared finger plethysmograph (FP) to
electrocardiogram (ECG) in providing accurate heart periods
for use in heart rate variability (HRV) calculations. In Experiment
1, simultaneous ECG and FP recordings were taken from 16 healthy
subjects at rest. In Experiment 2, 10 additional healthy subjects
were recorded at rest and during the Stroop Color-Word Test.
In both studies, high correlations were found between FP-derived
and ECG-derived band variance for high and low frequency HRV
at rest. But, during the Stroop task, correlations were strongly
diminished. In addition, under both conditions, HRV measures
were significantly higher using the FP signal. Thus, FP may
be adequate for determining HRV at rest, but, for experimental
use, ECG may still be recommended. Nonetheless, further studies
that include test–retest reliability assessment of both
data collection techniques are warranted before a more certain
determination can be made.