Lexical Decision Task

The lexical decision task (LDT), introduced by Meyer and Schvaneveldt (1971), is a foundational paradigm in psycholinguistics for measuring speed of access to the mental lexicon. On each trial a letter string appears at the centre of the screen and the participant presses F (word) or J (not a word) as quickly as possible.

Three stimulus categories are included:

• High-frequency words (e.g. LIGHT, TABLE): extremely common words that are recognised very rapidly.
• Low-frequency words (e.g. SCALD, KNAVE): genuine English words encountered less often in everyday text.
• Nonwords (e.g. GLAME, TRAND): pronounceable letter strings that follow English phonotactics but do not exist in the lexicon.

The key dependent measure is reaction time (RT) on correct trials. The classic findings are:

• Word frequency effect: high-frequency words are classified faster than low-frequency words (typically 100–200 ms in lab conditions) — the most replicated finding in the psycholinguistics literature.
• Lexicality effect: words are classified faster than nonwords, because lexical access succeeds rather than fails.

A variable foreperiod (blank screen, 500–1500 ms, balanced within each stimulus category) separates the fixation cross from stimulus onset, preventing anticipatory responses from contaminating the RT distribution.

Note on the stimulus list. The template ships with 30 demonstration stimuli (8 high-frequency, 8 low-frequency, 8 nonword main-task items; 6 practice items). For published research, replace the word list with stimuli drawn from validated frequency norms such as SUBTLEX-US (Brysbaert & New, 2009) or the English Lexicon Project (Balota et al., 2007), matched on word length and orthographic neighbourhood size.