Main -> In the Classroom: Sensation -> Vision Demos

Where rods and cones are and aren't (courtesy of Joseph Swope via PSYCHTEACHER listserv 9/10/13) 

Have a student sit in a chair facing the class.  Have another student stand behind him with a handful of different colored pens or markers.  It doesn't matter what color the ink is, the outside of the pens need to have different colors.  Have the student who is standing behind the seated student slowly bring one of the colored pens around in an arc to the seated student's peripheral vision.  Try to keep the colored pen about two feet away from the seated student's head.  The seated student will be able to see movement but will not be able to determine the color of the pen.  Have the seated student say stop when he sees movement.  Then have him guess the color.  He will be unable too, because the pen is not being focused on his retina.

Find your blindspot

You can find your blindspot at many pages including: Neuroscience for Kids or this Interactive Sensation Laboratory Exercises from Sage

Additionally, the Interactive Sensation Laboratory Assignments (ISLE) from Sage has other exercises on the Eye.

Investigating the implications of the varying concentrations of Rods and Cones throughout the Retina (courtesy of Manda Williamson)

1. After going over the locations of the greatest concentrations of rods (periphery) and cones (fovea), show students any image of the Mona Lisa. 

2. Ask they why, when you stare at her forehead and attend to her mouth (without directing gaze to her mouth) she seems to smile more than when you directly gaze at her mouth. 

(answer: when staring at her forehead we use rods to perceive the image of her mouth and the image is not as sharp and exaggerates the corners of her mouth; when staring directly at her mouth, our cones convey a more detailed image that resolves the mouth more clearly, indicating less of a smile)

For more information, please watch this video by Dr. Margaret Livinstone: https://www.youtube.com/watch?v=fwPqSxR-Z5E&t=4s