Senses and Perception Demonstrations

See also: The Brain and Nerves

Senses and perception activities explore how humans and animals detect and interpret information from the world around them. They are memorable because they connect directly to students’ own experiences of sight, sound, taste, touch, and smell.

Demonstration	Materials	Difficulty	Safety	Summary
Blind Spot	★☆☆	★☆☆	★★☆	Students use a simple card with a dot and an X to locate their blind spot. By covering one eye and moving the card at arm’s length, they observe how part of their vision disappears when light falls on the optic nerve instead of light-sensitive cells in the retina.
Rubber Hand Illusion	★★☆	★☆☆	★★☆	Students experience how the brain can be tricked into believing that a fake hand is their own. By synchronously stroking a hidden real hand and a visible fake hand, vision overrides touch and creates the illusion that the fake hand belongs to the participant.
Afterimage Illusion	★☆☆	★☆☆	★☆☆	Stare at a brightly colored image for a short time, then look at a blank white surface and observe a “ghost” image that appears in complementary colors. This activity demonstrates how cone cells adapt and how the opponent process in vision creates negative and positive afterimages.
Change Blindness	★☆☆	★☆☆	★☆☆	This demonstration presents two nearly identical images that alternate with one small change between them. Observers often take a long time to notice the difference, highlighting the limits of visual attention and the phenomenon known as change blindness.
Color Changing Water	★☆☆	★☆☆	★☆☆	A glass of blue-colored water is placed inside a bowl, and the bowl is then filled with yellow-colored water. When looking through the bowl, the overlapping yellow and blue liquids appear green, even though the water in each container stays its original color.
Dropping Ruler Reaction Time	★☆☆	★☆☆	★☆☆	Students test their reaction speed by trying to catch a falling ruler as quickly as possible. The activity demonstrates how the nervous system processes information from the eyes to the brain and then to the muscles to produce a response.
Ebbinghaus Illusion	★☆☆	★☆☆	★☆☆	The Ebbinghaus Illusion shows how surrounding context changes our perception of size. Two identical central circles appear different in size when one is surrounded by larger circles and the other by smaller circles.
Evaporative Cooling with Liquids	★☆☆	★☆☆	★☆☆	This activity demonstrates how evaporation causes cooling by comparing how water and rubbing alcohol feel when placed on the skin. As the liquids evaporate, they remove heat from the surface, showing how sweating helps regulate body temperature.
Flying Optical Illusion	★★★	★★☆	★☆☆	A large mirror creates the illusion that a person’s leg reflection is actually their other leg, making it appear as though both legs lift off the ground and the person is flying.
Genie in the Bottle Rope Trick	★★☆	★☆☆	★☆☆	A hidden ball inside a bottle creates friction against a rope, making it appear that the rope is magically suspended in the bottle. This trick demonstrates how frictional forces resist motion between surfaces.
Inattentional Blindness	★☆☆	★☆☆	★☆☆	Inattentional blindness occurs when a person fails to notice something in plain sight because their attention is focused on another task. This demonstrates how limited attentional control can cause us to miss significant details in our environment.
Learning New Skills Mirror Maze	★★☆	★☆☆	★☆☆	In this activity, participants trace a star shape while only viewing their hand’s reflection in a mirror. The task is repeated across multiple trials and days, demonstrating motor learning, memory, and adaptation as performance improves over time.
Ponzo Illusion	★☆☆	★☆☆	★☆☆	The Ponzo Illusion demonstrates how our perception of size is influenced by background context. Two identical horizontal lines appear different in length when placed between converging lines that mimic perspective, with the top line seeming longer.
Reaction Time Under Fatigue	★☆☆	★☆☆	★☆☆	Students measure their reaction time before and after an induced fatigue condition and compare changes in average reaction time and variability. The class explores how mental or physical fatigue influences response speed and consistency.
Serial Position Effect	★☆☆	★☆☆	★☆☆	This demonstration shows that people recall items at the beginning and end of a sequence better than items in the middle. It illustrates how primacy and recency shape memory when information is presented in order.
Smelly Balloons	★☆☆	★☆☆	★☆☆	Students place small amounts of scented liquids inside latex balloons, inflate them, and identify the scent over time. The activity models diffusion across a barrier and introduces terms like concentration gradient, semi-permeable membrane, and equilibrium.
Sound Localization	★★☆	★☆☆	★☆☆	Students investigate how two ears help the brain locate where a sound comes from by comparing the tiny time and loudness differences that reach each ear. Using a stethoscope headset connected to tubing, one partner taps at different positions while the listener identifies whether the sound is from the left or right.
Stroop Effect	★☆☆	★☆☆	★☆☆	The Stroop Effect is a demonstration of how conflicting information from reading and color recognition interferes with response time. When the name of a color is printed in a different color ink, people take longer to identify the ink color than to read the word itself.
Taste and Smell Connection	★☆☆	★☆☆	★☆☆	This activity demonstrates how smell influences our sense of taste. By holding the nose while eating candy, participants notice that flavors become muted and difficult to identify until scent molecules reach the olfactory system.
The McGurk Effect	★☆☆	★☆☆	★☆☆	The McGurk effect occurs when conflicting visual and auditory cues lead the brain to misinterpret what sound is being heard. By combining mismatched audio and video of a spoken word, students can observe how visual information influences auditory perception.
Two Point Discrimination	★☆☆	★☆☆	★☆☆	Students test how well different areas of the body can distinguish between one and two points of touch using a simple two-point discrimination device. The activity demonstrates the uneven distribution of touch receptors across the skin and why some areas are more sensitive than others.
Visual and Auditory Reaction Time	★☆☆	★☆☆	★☆☆	Students measure and compare their visual and auditory reaction times by catching a falling meter stick, analyzing how quickly they respond to different types of stimuli. The experiment highlights how the nervous system detects, processes, and responds to environmental signals.

Materials
★☆☆ Easy to get from supermarket or hardware store
★★☆ Available in most school laboratories or specialist stores
★★★ Requires materials not commonly found in school laboratories

Difficulty
★☆☆ Can be easily done by most teenagers
★★☆ Available in most school laboratories or specialist stores
★★★ Requires a more experienced teacher

Safety
★☆☆ Minimal safety procedures required
★★☆ Some safety precautions required to perform safely
★★★ Only to be attempted with adequate safety procedures and trained staff