1. A computer-implemented method for mental state analysis comprising: obtaining video of an individual; analyzing the video to determine heart rate information, wherein the analyzing includes: evaluation of phasic and tonic heart rate responses; identifying a location of a face of the individual in a portion of the video; separating pixels, from the location of the face, from the video of the individual, into at least a green pixel temporal intensity trace; training a statistical classifier, wherein the training is learned from a data set consisting of human blood volume pulse synchronized face videos; and recognizing a pulse, from the video of the individual, using the statistical classifier, by learning patterns of variability in the mean of the pixel temporal intensity trace; correlating the heart rate information to a stimulus that the individual is encountering; and inferring, using one or more processors, mental states of the individual based on the heart rate information, wherein a time lag between the stimulus and the heart rate information is factored into the inferring.