36 optical illusions. How creative are you. Cognitive Brain Test. Great for challenging students and clients. May be used in Speech Therapy for information processing activities, visual scanning, expressive, cognitive and/or entertainment. This activity starts with a discussion on 3 types of thinkers, an index of all illusion photos, drawings and ends with a surprise photo and a positive note. Note: All photos are royalty free, creative commons or have been purchased. Photo credits are in the bo