I kind of familiar with wavelet transform (I just used it in code but do not have a deep understanding about it). I've been reading an article and came across this sentence:
where 4Fs is the length of the Morlet wavelet with -2 to 2 second support with sampling frequency Fs
and I can't figure out what the -2 second means. By the way the article link is: Deep Convolutional Neural Networks for Brain Computer Interface using Motor Imagery