LexOPS

LexOPS is an R package for generating matched stimuli for factorial design experiments. You can use the functions on any dataframe, but there is an inbuilt database of example features for English words for psycholinguistics studies in English (LexOPS::lexops).

Installation

LexOPS can be installed as an R package with:

devtools::install_github("JackEdTaylor/LexOPS@*release")

How to Use

📖 In-depth walkthrough of the package: https://jackedtaylor.github.io/LexOPSdocs/

🎓 Paper about the package: Taylor, Beith, and Sereno (2020)

TL;DR

LexOPS makes it easy to generate matched stimuli in a reproducible way. The functions work on any dataframe, but there is an inbuilt dataset, LexOPS::lexops, containing psycholinguistic variables for English words.

The “Generate Pipeline”

The following example pipeline generates 50 words per condition (200 in total), for a study with a 2 x 2, syllables (1, 2) by concreteness (low, high) design. Words are matched by length exactly, and by word frequency within a tolerance of ±0.2 Zipf.

library(LexOPS)

stim <- lexops %>%
  split_by(Syllables.CMU, 1:1 ~ 2:2) %>%
  split_by(CNC.Brysbaert, 1:2 ~ 4:5) %>%
  control_for(Zipf.SUBTLEX_UK, -0.2:0.2) %>%
  control_for(Length) %>%
  generate(n = 50)

#> Generated 50/50 (100%). 157 total iterations, 0.32 success rate.

A preview of what was generated:

# create a table of the first 5 rows of the output
stim %>%
  head(5) %>%
  knitr::kable()

item_nr	A1_B1	A1_B2	A2_B1	A2_B2	match_null
1	fresh	frame	basis	river	A1_B2
2	gist	cuff	akin	tuba	A2_B1
3	fate	slip	rely	lily	A1_B1
4	shrewd	wrench	equate	muzzle	A2_B2
5	famed	reins	ethic	totem	A2_B1

Review Generated Stimuli

The plot_design() function produces a plot summarising the generated stimuli.

plot_design(stim)

Convert to Long Format

The long_format() function coerces the generated stimuli into long format.

# present the same 20 words as in the earlier table
long_format(stim) %>%
  head(20) %>%
  knitr::kable()

item_nr	condition	match_null	string	Zipf.SUBTLEX_UK	Length	Syllables.CMU	CNC.Brysbaert
1	A1_B1	A1_B2	fresh	4.893319	5	1	1.97
1	A1_B2	A1_B2	frame	4.755413	5	1	4.30
1	A2_B1	A1_B2	basis	4.625308	5	2	1.83
1	A2_B2	A1_B2	river	4.926899	5	2	4.89
2	A1_B1	A2_B1	gist	2.974489	4	1	1.81
2	A1_B2	A2_B1	cuff	3.272077	4	1	4.61
2	A2_B1	A2_B1	akin	3.083126	4	2	1.71
2	A2_B2	A2_B1	tuba	2.951008	4	2	4.86
3	A1_B1	A1_B1	fate	4.224395	4	1	1.53
3	A1_B2	A1_B1	slip	4.332324	4	1	4.10
3	A2_B1	A1_B1	rely	4.318882	4	2	1.93
3	A2_B2	A1_B1	lily	4.253363	4	2	4.69
4	A1_B1	A2_B2	shrewd	3.244739	6	1	1.92
4	A1_B2	A2_B2	wrench	3.150581	6	1	4.93
4	A2_B1	A2_B2	equate	2.976769	6	2	1.93
4	A2_B2	A2_B2	muzzle	3.066804	6	2	4.59
5	A1_B1	A2_B1	famed	3.415895	5	1	1.81
5	A1_B2	A2_B1	reins	3.327180	5	1	4.56
5	A2_B1	A2_B1	ethic	3.303191	5	2	1.59
5	A2_B2	A2_B1	totem	3.239804	5	2	4.00

Shiny App

The package has an interactive shiny app, which supports most code functionality, with useful additional features like visualising distributions and relationships. It’s a friendly front-end to the package’s functions. A demo version of the LexOPS shiny app is available online at https://jackt.shinyapps.io/lexops/, but it is faster and more reliable to run it locally, with:

LexOPS::run_shiny()