	
	
	
	
	IDENTIFICATION OF LETTERS AND LETTERS WITHIN WORDS

  
  
  Your task is to identify a briefly presented target letter, either 
  presented on its own, or embedded within a four letter word. The 
  target letter will be followed almost immediately by a `mask' 
  consisting of 4 X's, occurring at exactly the same place on the 
  screen that the letter or word appeared, so that the target letter 
  (and surrounding word) is obscured.
 
  
  A pair of letters will be presented along with the mask to act as 
  response alternatives. One letter of the pair will match the target 
  letter, the other will not. They are presented so that one of the 
  pair is just above where the target letter was, and the other just 
  below it.
  
  
  
  
  
  
  For example, if the target letter was `c' it could be presented 
  either on its own, or embedded in the word `face'. One response 
  alternative would be `c' (correct) and the other might be `t' 
  (incorrect).
  
 
 
	 TARGET         c               or              face                                 
 
		
		
			c                                 c
	 MASK         XXXX                              XXXX
			t                                 t

			 
  
  
  
  
  

  The choice is signaled by pressing either one of a pair of keys 
  arranged one above the other. 
 
  Pressing the upper key indicates that the choice is upper letter 
  (`c'). 
 
  Pressing the lower key indicates that the choice is the lower letter 
  (`t').
 
  _______________________________________________________________________
  For ease of response, different keys are used by left and right handers
 
     For LEFT handers the upper key is  Q, the lower key is A
     For RIGHT handers the upper key is P, the lower key is L
 
  The responses are made using the first and second fingers of one hand.
  ________________________________________________________________________
 
 
 

  During practice trials the tone will be sounded every time you make 
  an error. 
  
  PRESS 'L' TO HEAR THE TONE NOW. 
  
  Feedback will NOT be given during experimental trials.

  REMEMBER:
 
  If you are RIGHT-HANDED
 
	 press P if upper letter matches target 
	 press L if lower letter matches target
  
  If you are LEFT-HANDED
 
	 press Q if upper letter matches target
	 press A if lower letter matches target
 
 
  
  
  
  
  
  
  
  You will find that the exposure times of the target letters are very short, 
  so that you may not be able to recognize them.
  
  
  IF YOU DO NOT KNOW WHICH LETTER THE TARGET WAS, GUESS!
  
  
  It is important that you do this, since the next trial will only start 
  after a response has been made. The program also measures response times 
  and very long response times and very long response times will distort 
  the means - so respond as fast as you can.
 
 
 
 
 
 
	
	
	
	

	
	You are now ready to go on to do the practice trials.
 
   You will be given two blocks of practice trials, before going on to 
   the experimental trials. There are 28 trials in a block, and at the 
   end of each block you will be offered a rest.
 
  
 
 
     You can read the instructions again by pressing 'Q' and 'A'.
    
	 
	     If you understood the instructions you can 
	      start the practice trials by pressing 'X'
 
