From: PSYCHOBOX‚ A BOX PSVHOLOGICAL GAMES. Edited by: Mel GOODING. Shambala Publication . 2004

This test is best administered by masking the card and successively uncovering from the top each row of three panels. Moving as fast as you can from top left to bottom right. say out loud how many objects there are in each panel.
You are likely to have made an error. hesitated or taken longer on reaching the last two panels. This is because the objects in each panel are Arabic numerals whose names and meaning are those of numerical quantities that differ from the actual number of objects displayed. The objects in the preceding panels are themselves irrelevant to the numerical quantity task. and are not. in fact. quite so easy to name as the Arabic numerals. They do not interfere with the task of saying the number as we do not have to make any special effort to ignore them. We are therefore unprepared to ignore the Arabic numerals when they occur. and when we see them their meaning is immediately understood and made available for speech. The principle at work here is similar to that in the Colour Naming tasks: our intention is to apprehend numerical quantity and say out loud the number of objects we see. and that is easy when we are presented with a small number of objects whose meaning is not in the domain of number. We apprehend immediately the quantity of up to five closely arrayed objects. When the objects whose number is to be stated are themselves numerals i.e. in the domain of number. we have to make a special effort to ignore them. and interference occurs at the level of speech. This demonstrates once more the difficulty we have in se‎lectively attending to one aspect of a display and totally ignoring another aspect.
Freud was deeply interested in those speech errors that occur when what is produced is different from what was intended. seeing it as revelatory of what the speaker had in mind irrespective of the conscious intention to say something else. This was a central theme of his classic The Psychopathology of Everyday Life (1904). Research indicates. however. that many errors produced by speech processes might merely reflect an innocuous aspect of the nervous system as such.