Hold a picture in the minds eye for seven seconds.
Its a great and usually quite difficult achievement on the way to psychic ability.
With eyes closed and relaxed, focus on breathing until breathing is the only thing in the mind.
Then focus the mind on a simple shape or image. A cross, a circle, or etc.
Work toward making the shape as visual as a dream image, actually seen with the eyes closed but originating in the mind.
The object will try to shrink and grow, rearrange itself, retreat from vision and reappear. The goal of the exercise is to prevent this and hold the image steady.
Strange sensations may occur as the simple image maintains solidity, such as a perception of locking or absorption of the mind with the image.
Seven seconds, steady unchanging image is the goal, this could take months or years.