Even Senses Get Tired

    Optic Fatigue

Look at the picture below for about 30 seconds. Then look at the white space next to the image. You should then see a negative after image. You should see the flag in its correct colors.

 How it works:

 Color sensitive photoreceptors in the retina respond to the incoming light when focusing on the flag. Photoreceptors become fatigued by staring at the image. The fatigue or desensitization is strongest for the cells that view the brightest part of the figure, and weaker for those that view that darker part of the figure. When switching to the white paper, the less fatigued cells take over and produce the negative afterimage of the correct colors of the flag. The green stripes will show red, the black stripes and stars will show white, and the yellow background of the stars will show blue.

Look at the image for 30 seconds, then look at the white space next to the image. The lightbulb should appear to glow. Which is the negative afterimage.

    Sensory Fatigue

We are going to induce sensory fatigue with the girls by using varying water temperatures. We are going to fill 3 buckets with water. One bucket will have a cool water temperature, one will have a warm water temperature, and the last one will have a neutral water temperature. First we will have the girls put their one of their hands in the bucket of warm water and one of their hands in the bucket of cool water simultaneously. They will feel the difference in temperatures, but after time the water in the buckets will feel like the same temperature. Next we will have the girls take their hands out of the buckets of water and have them place both of their hands in the neutral water temperature bucket. They should then be able to feel the difference in temperatures. One hand should feel cold and one hand should feel warm, thus exhibiting sensory fatigue.

Step One: Grab three buckets or bowls

Step Two: Fill one bucket with 70 F (20 C) temperature water

               Fill a second bucket with 90 F (30 C) temperature water

               Fill the last bucket with 105 F (40 C) temperature water

Step Three: Label the buckets according to temperature

Step Four: Immerse one hand into the 70 F bucket and the other hand into the 105 F bucket. Keep hands submerged for 2 minutes or until both hands no longer feel warm nor cold.

Step Five: Remove hands and place them into the 90 F bucket. It should feel as though the hand that was in the warm water is now cold and the hand that was in the cold water is now warm.

Why does this happen?

When you first put your hands in the water, your sensory receptors began noticing that the water was either warm or cold. As your hands stayed in the water, your receptors gradually adapted to the temperature because it hadn't changed. It's like swimming; at first the water feels cold, but eventually you don't notice it. However, when you removed your hands and placed them into the 90 F bucket, you felt something. Your cold hand, which had become bored with the cold water, jumped to life and began telling you that the water was warm. Likewise, your warm hand sensed that the water was cold.