| CLE
| Attention
| Lexical Decision
A lexical decision is deciding if a string of letters is a word or not, e.g., dog vs hra. It was introduced by Meyer and Schvaneveldt (1971) in the early 1970's. This decision seems a trivial task but it turns out that it it has helped illustrate many fundamental processes in the cognitive tasks of reading words. For example, it turns out that the two decisions, word or nonword, are not mirror images. Due to all the practicing in reading, it is much easier to determine if a string of letters is a word than not a word. In this expeirment, the lexical decision is combined with a priming task. Before you make your lexical decision, you will be presented with a string of letters, perhaps a word, perhaps not. If a word is the prime stimulus, it might be in some way related to the word you have to make the decision. The questions is, how does the type of prime influce how fast you respond?
You can adjust several parameters to design your own version of the experments. The settings are discussed below.
The stimulus settings include the following:
New Study: when the study has been finished, you can press this button to
start a new experiment.
Reset Stimulus: press this button to reset to the default conditions.
Font Size: the size of the letters for the words.
Background Gray Level: the brightness the background behind the word
from back to white.
Word Position Horizontal (relative): The left/right position of the word relative to the screen
width. The lower the value, the more towards the left.
Fixation Duration (ms): The duration of the fixation mark.
Trial Delay before Fixation (ms): The duration delay before the fixation mark
and between the words.
Stimulus On Till Response: Select to have the stimulus on till the participant
responds.
Duration of Stimulus (ms): If the above item is unselected, use this setting
to adjust how long the stimulus stays on.
Duration of Interstimulus Interval (ISI) (ms): This changes the time between
the prime and the stimulus you need to respond to.
New Study: when the study has been finished, you can press this button to
start a new experiment.
Reset Method: press this button to reset to the default conditions.
Type of Primes: This is how the prime is related to a word, if a word follows. It is still
possible to have nonwords in each condition, this is just a control to make sure the words for each class
of prime is selected carefully.
Number of Trials/condition: How many trials in each condition.
Change the settings below to alter the stimulus parameters in this experiment.
Change the settings below to alter the parameters of the experimental method.
Below, press the spacebar or the Open Experiment Window button on the screen to open the window where the experiment will run. When this screen opens, press the spacebar or click the "Start" button to begin the experiment. Press the space bar to begin the experiment. A fixation mark will appear for the indicated time. There there will a word presented briefly. This is the prime and no response if required. After the interstimulus interval will be presented the target stimulus. Your task is to quickly and accurately indicate if the stimulus is a word or nonword. You may respond by pressing either the buttons at the botton of the screen or the F or W keys for words or the J or N keys for nonwords. There are instructions above the "Start" button. Read them to know how to perform the experiment. Keep your eyes fixated on the red plus sign in the middle of the screen.
Your data will be presented on the results tab. The x-axis will have the prime target word relationship relationship. You can look at both reaction time and accuracy. To download your trial-by-trial, press the Show Data link. To download the summary data press the Show Summary link. This data will be stored in a csv format readable by most spreadsheet and statistical programs.
Meyer, D.E. & Schvaneveldt, R.W. (1971). Facilitation in recognizing pairs of words: Evidence of a dependence between retrieval operations. Journal of Experimental Psychology, 90, 227–234.