Surprise them by telling them the ways they were thinking. As you ask the person to think of shapes, discreetly trace the shapes in the air with your hands, unconsciously planting the image in their mind. This is called subliminal programming and it's a common (incredibly cool) mentalism technique. Ask someone to think of a shape in their head.
A simple shape like a square, but not a square. This simple suggestion will often encourage people to think of a triangle, just as they did with Elephant above. Mentalism is a form of magic that uses psychological principles to create an illusion. It is a type of performing art that uses the power of suggestion and psychology to convince the audience that an event or object has occurred without using any physical medium.
Mentalism has swept the world by storm, and it's not just for those who engage in magic and mind reading tricks. The most important thing to do when performing these magic tricks is to focus and keep your mind clear. To do this, try not to think about what will happen if you succeed or fail. Instead, focus on the moment and what you're doing at the time.
The most common categories of mentalism include telepathy, clairlecture, precognition, mind control, and hypnosis. The most popular type of performance is mind reading, where the magician will point out precisely what the audience thinks.