Compute Intersubject Correlation (ISC)

Description

Computes ISC using either the pairwise correlation method or the leave-one-out method. The pairwise method computes a full correlation matrix and averages Fisher z-transformed values. The leave-one-out method computes the correlation of each participant’s time series with the mean of all others.

Usage

calculate_isc(
  data_matrix,
  method = c("pairwise", "leave-one-out"),
  cor_method = c("pearson", "spearman"),
  return_matrix = FALSE
)

Arguments

data_matrix	A numeric matrix or data.frame where rows represent time points and columns represent participants.
method	A string specifying the ISC computation method. Options are ‘"pairwise"’ (default) or ‘"leave-one-out"’.
cor_method	Correlation type passed to [stats::cor()]. One of ‘"pearson"’ (default) or ‘"spearman"’.
return_matrix	Logical. If ‘TRUE’ and ‘method = "pairwise"’, return the full participant-by-participant correlation matrix (self-correlations set to NA) instead of a summary vector. Ignored for ‘method = "leave-one-out"’.

Value

A named numeric vector of ISC values (one per participant), or a correlation matrix if ‘return_matrix = TRUE’.