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Response-time distributional checks

Source: R/check_rt.R
check_rt.Rd

Scans response times (RTs) for three kinds of pathology:

Usage

check_rt(
  responses,
  method = c("2ifc", "briefrc"),
  col_participant = "participant_id",
  col_rt = "rt",
  fast_threshold = 200,
  slow_threshold = 5000,
  max_fast_frac = 0.05,
  max_slow_frac = 0.05,
  min_cv = 0.1,
  ...
)

Arguments

responses

A data frame of trial-level responses.

method

Either "2ifc" or "briefrc". Currently informational.

col_participant

Participant id column.

col_rt

RT column (required; the check aborts if NULL).

fast_threshold

Milliseconds. Trials faster than this count as "fast". Default 200.

slow_threshold

Milliseconds. Trials slower than this count as "slow". Default 5000.

max_fast_frac

Fraction. Participants with more than this fraction of fast trials are flagged. Default 0.05 (warn) / 0.15 (fail).

max_slow_frac

Fraction. Participants with more than this fraction of slow trials are flagged. Default 0.05 (warn).

min_cv

Numeric. Participants with coefficient of variation of RT below this are flagged. Default 0.10.

...

Unused.

Value

An rcdiag_result() object. data$per_participant has one row per participant with columns: n_trials, mean_rt, median_rt, sd_rt, cv_rt, pct_fast, pct_slow, is_flagged.

Details

  1. Implausibly fast responses (rt < fast_threshold, default 200 ms). These usually indicate the participant clicked without reading the stimulus.

  2. Implausibly slow responses (rt > slow_threshold, default 5000 ms). These suggest distraction or a task pause.

  3. Abnormally low within-participant RT variability (coefficient of variation below min_cv, default 0.10). A near-constant RT is a hint that the participant is responding mechanically.

Examples

set.seed(1)
responses <- data.frame(
  participant_id = rep(1:3, each = 100),
  stimulus       = rep(1:100, 3),
  response       = sample(c(-1, 1), 300, replace = TRUE),
  rt             = c(
    exp(rnorm(100, 6.7, 0.4)) + 100,   # normal
    rep(150, 100),                     # all fast and constant
    exp(rnorm(100, 6.7, 0.4)) + 100
  )
)
check_rt(responses, col_rt = "rt")
#> [FAIL] Response times
#>   1 of 3 participants exceed 5% fast trials (< 200 ms).
#>   0 of 3 participants exceed 5% slow trials (> 5000 ms).
#>   1 of 3 participants have RT coefficient of variation below 0.1.
#>   1 participants exceed 15% fast trials (severe).