Note that this reference documentation is identical to the help that is displayed in MATLAB when you type “help ft_connectivity_psi”.

  FT_CONNECTIVITY_PSI computes the phase slope index from a data-matrix
  containing the cross-spectral density. It implements the method described
  in: Nolte et al., Robustly estimating the flow direction of information
  in complex physical systems. Physical Review Letters, 2008; 100; 234101.
  Use as
    [c, v, n] = ft_connectivity_psi(input, ...)
  The input data input should be organized as
    Repetitions x Channel x Channel (x Frequency) (x Time)
    Repetitions x Channelcombination (x Frequency) (x Time)
  The first dimension should be singleton if the input already contains an
  Additional optional input arguments come as key-value pairs:
    nbin			=	scalar, half-bandwidth parameter: the number of frequency bins
 								across which to integrate
    hasjack		= 0 or 1, specifying whether the repetitions represent
                leave-one-out samples (allowing for a variance estimate)
    feedback	= 'none', 'text', 'textbar' type of feedback showing progress of
    dimord		= string, specifying how the input matrix should be interpreted
    powindx   =
    normalize =
  The output p contains the phase slope index, v is a variance estimate
  which only can be computed if the data contains leave-one-out samples,
  and n is the number of repetitions in the input data. If the phase slope
  index is positive, then the first chan (1st dim) becomes more lagged (or
  less leading) with higher frequency, indicating that it is causally
  driven by the second channel (2nd dim)