Lexical Decision Tasks: A Deep Dive

What is a Lexical Decision Task?

A Lexical Decision Task (LDT) is a common experiment in psycholinguistics where participants are presented with a mix of real words and non-words (letter strings). The goal is for the participant to quickly and accurately determine if the presented string is a valid word in their language.

Famous Studies Involving the LDT

The LDT has been central to numerous cognitive psychology studies over the years. For instance:

• Meyer & Schvaneveldt (1971): This seminal study showed that participants could identify related words (like "doctor" and "nurse") faster than unrelated word pairs. This finding shed light on the structure of semantic memory.
• Balota & Chumbley (1984): By using the LDT, these researchers were able to demonstrate the effect of word frequency on word recognition.

Common Variants of the LDT

Over time, various modifications to the standard LDT have emerged. Some popular variants include:

• Primed LDT: Prior to seeing the target word/non-word, participants are presented with a "prime" word. This allows researchers to investigate how related primes can influence lexical decision times.
• Masked LDT: The target word/non-word is presented briefly and then masked (covered) by another stimulus, making it harder for participants to recognize the word.

Try the Lexical Decision Task

Want to experience the LDT firsthand? Give it a try below:

Behind the Scenes: Coding the LDT

Curious about how such an experiment is coded? Here's a snippet of the code used for the demo above:

// Initialize the timeline
    var timeline = [];

    // Instructions
    var instructions = {
      type: 'html-keyboard-response',
      stimulus: '<p>In this task, you will see a series of letter strings.</p>' +
                '<p>Your job is to press "W" if the string is a word, and "N" if the string is not a word.</p>' +
                '<p>Press any key to begin.</p>',
    };

    timeline.push(instructions);

    // List of stimuli
    var stimuli = [
        { stimulus: "table", word: true },
        { stimulus: "chair", word: true },
        { stimulus: "dnfke", word: false },
        { stimulus: "glort", word: false }
        // ... add more stimuli here
    ];

    // Define the LDT
    var ldt = {
      type: 'html-keyboard-response',
      stimulus: jsPsych.timelineVariable('stimulus'),
      choices: ['w', 'n'],
      trial_duration: 1500,
      data: {
          word: jsPsych.timelineVariable('word')
      },
      on_finish: function(data){
          data.correct = (data.response == 'w' && data.word) || (data.response == 'n' && !data.word);
      }
    };

    // Add the LDT to the timeline with the stimuli
    timeline.push({
      timeline: [ldt],
      timeline_variables: stimuli,
      randomize_order: true
    });

    // Run the experiment
    jsPsych.init({
      timeline: timeline,
      on_finish: function() {
        jsPsych.data.displayData();
      }
    });