  Computational ghost imaging relies on the decomposition of an image into
patterns that are summed together with weights that measure the overlap of each
pattern with the scene being imaged. These tasks rely on a computer. Here we
demonstrate that the computational integration can be performed directly with
the human eye. We use this human ghost imaging technique to evaluate the
temporal response of the eye and establish the image persistence time to be
around 20 ms followed by a further 20 ms exponential decay. These persistence
times are in agreement with previous studies but can now potentially be
extended to include a more precise characterisation of visual stimuli and
provide a new experimental tool for the study of visual perception.
