As this clearly demonstrates, there are two distinct forms of thinking, verbal and visual. This can be clearly demonstrated in an n-back test that uses visual images. Imagine a computer screen that flashes images of various things, perhaps cartoon images of carrots, apples, cats, mice, televisions, radios and stars. An n-back test flashes such images to the subject for a limited period of time, and requires the subject to hit a button if the image currently being displayed is the same image that was displayed n previous images prior. A person can solve this task either with their visuospatial sketchpad or with their phonological loop. Somebody who solves this with their visuospatial sketchpad will imagine the sequence of flashed images in their mind n + 1 at a time, and compare the current object in their memory to the furthest object back, then after answering they will shift the images and repeat with the new input. A person who solves this problem with their phonological loop will remember the verbal labels representing the objects. So in the 2-back sequence carrot, apple, carrot, television, star, television they will think like this Round 1: Carrot (remember first), Apple (remember second) Round 2: (Carrot?) Carrot (match, remember carrot first), (Apple?) television (no match, forget apple, remember television second) Round 3: (Carrot?) Star (no match, forget carrot, remember star first), (Television?) television (match, remember television second) A person who solves this problem visually could do it like this (imagine all text == the image it labels) Round 1: carrot, apple, carrot (match identified, shift 1 to the left) Round 2: apple, carrot, television (no match identified, shift 1 to the left) Round 3: carrot, television, star (no match identified, shift 1 to the left) round 4: television, star, television (match identified, shift 1 to the left) The same thing can be done with reverse digit span, in which a person is orally presented with a series of numbers and then asked to recite them backwards. A visual strategy to solve this problem is visualizing the numbers forward as they are recited, and then reading them in reverse: 1, 20, 30, 40 (read backwards from 40 to 1) a verbal technique to solve this problem is looping the numbers verbally as they are presented forward: 1 1, 20 1, 20, 30 1, 20, 30, 40 and then going backwards: 1, 20, 30, say 40 1, 20, say 30 1, say 20 say 1 yet another example is reciting the alphabet. When asked to say what comes after a certain letter, some people will verbally loop the alphabet forward to the letter + 1 a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p is after o other people will visually recall the alphabet and simply look to the right of p, and say what they see which is o. In the first case the problem is solved with long term verbal recall + phonological looping, in the second case the problem is solved with long term visual recall + the visuospatial sketchpad. So clearly there are vast differences between verbal and visual thinking, and it is possible to think in either.