Creates a new HRF object representing a response to a sustained (blocked) stimulus by convolving the input HRF with a boxcar function of a given width.
Arguments
- hrf
The HRF object (of class `HRF`) to block.
- width
The width of the block in seconds. Every positive width is integrated, including widths smaller than `precision`. Zero retains the original impulse response.
- precision
The sampling precision in seconds used for the internal convolution (default: 0.1).
- half_life
The half-life of an optional exponential decay applied during the block (default: Inf, meaning no decay).
- summate
Logical; if TRUE (default), responses within the block are integrated (summed). If FALSE, the integrated response is divided by the block width to obtain a temporal average. With finite `half_life`, decay attenuates the integrand but does not change this divisor. This does not fix peak height: longer blocks can have smaller peaks. Use `normalize = TRUE` for unit-peak scaling.
- normalize
Logical; if TRUE, scale each basis independently by its peak absolute value on a fixed reference grid over the full blocked span (the original span plus `width`). Uses the same approximately 0.02-second reference spacing as [normalize_hrf()] with `"unit_peak_per_basis"`. The factors are computed once at construction, so scalar, vector, and chunked queries have the same scale. Signs are preserved and zero bases remain zero. Default: FALSE.
See also
Other HRF_decorator_functions:
lag_hrf(),
normalise_hrf(),
normalize_hrf()
Examples
blocked_spmg1 <- block_hrf(HRF_SPMG1, width = 5)
t_vals <- seq(0, 30, by = 0.5)
plot(t_vals, HRF_SPMG1(t_vals), type = 'l', col = "blue", ylab = "Response", xlab = "Time")
lines(t_vals, blocked_spmg1(t_vals), col = "red")
legend("topright", legend = c("Original", "Blocked (width=5)"), col = c("blue", "red"), lty = 1)
