Mini Lesson 2
- 2. Absolute Threshold The weakest amount of a stimulus that a person can detect. Sight Seeing a candle flame 30 miles away on a clear night Hearing Hearing a watch ticking 20 feet away Touch Feeling a bee’s wing falling a distance of 1cm onto your cheek Smell Smelling one drop of perfume in a three room house Taste Tasting one teaspoon of sugar dissolved in two gallons of water
- 3. Difference Threshold The smallest amount of change in a physical stimulus that a person can detect. This is also called the “just noticeable difference.” If someone turns the music up slowly, at what point do you notice it has become louder? If you hold a handful of sand, and someone adds one grain at a time to the pile, when do you notice it has become heavier? If your best friend trims a half inch off of their hair, will you notice the difference?
- 4. Absolute Threshold Difference Threshold The weakest amount of a stimulus you can detect. The smallest amount of change in a stimulus you can detect. Review: I can see a candle flame 30 miles away! (But not 31 miles away!) I can see a difference between these two color hues: But not between these two:
- 5. Signal Detection Theory It is impossible to process every simultaneous stimulus equally in our brains. Instead, we focus our attention on certain things while at the same time attempting to ignore the flood of information entering our senses. When we do this, our brains decide what is important to sense and what should be in the background. This concept is referred to as signal detection because we detect what we want to focus on, and ignore everything else.
- 6. Sensory Adaptation Sensory adaptation is our ability become to less sensitive to an unchanging stimulus. Ever wonder why we notice certain smells or sounds right away and then after a while they fade into the background? If a stimulus has become redundant or remains unchanged for an extended period of time, we begin to ignore it. Without sensory adaptation, you would feel the constant pressure of clothes on your body - you would be bombarded with sensory information.
- 7. Sensory Adaptation Clock ticking in the room? Funny smell in the room? Eventually you will stop noticing them. Eating spicy food? Eventually it will taste less spicy. Step into a hot bath? At first it might feel too hot, but eventually it feels cooler. Walk into a dark room? At first it will be too dark to see, but then it becomes lighter. These are examples of sensory adaptation.
- 8. Signal Detection Theory Sensory Adaptation When multiple stimuli are present, this is our ability to recognize some signals, while ignoring others. Our ability to become less sensitive to an unchanging stimulus over time. Review: I detected the ring of my cell phone, even though there are other auditory stimuli in the room! That construction next door is so LOUD and distracting! Fifteen Minutes Later… Oh! I forgot there was construction going on outside. I started to ignore it.