The Senses

discuss NOW with the person beside you: Which sense would you be most willing to give up? Why? Which one would you least like to lose? Why?

The Senses The senses are the human brain’s connection to the outside world. Sight Hearing Taste Smell Touch

Sensation: Is bottom-up processing Starts with the senses - In other words, your brain takes in information to help it understand the world

– this is called transduction What is Sensation? we detect physical energy (stimulus) from the environment through our sensory organs (eg. Eye) sensory organs have sensory receptors the physical energy is then converted into neural signals (these are signals sent to the brain) – this is called transduction

Sensory Receptors The stimulus is interpreted by the appropriate sensory receptor (eg. You touch a hot stove), the message travels to “sense-specific” areas of the brain the message travels along sensory neurons our brain receives and interprets the neural signals, causing sensation.   (OW! That stove was hot!)

Sensory Adaptation Diminished sensitivity as a result of constant stimulation. -Ever forgotten you are wearing a ring or a watch? -Ever gotten used to a smell? After drinking tea with lemon, a grapefruit won’t taste so sour. After eating a doughnut, however, a grapefruit will taste extremely sour.

Turn to the person beside you and say TRANSDUCTION is when your sensor organs turn physical energy from your senses into electrical energy that goes to your brain!!! SENSORY ADAPTATION is when you don’t sense something because you have become used to it

Just noticeable diffErencE http://highered.mheducation.com/sites/dl/fr ee/007312387x/334868/webers_mx.swf Experiment with sounds Difference

Just noticeable differencE The minimum difference that a person can detect between two stimuli 50% of the time. Also known as difference threshold This relates to Weber’s Law

Weber’s Law The idea that, to perceive a difference between two stimuli, they must differ by a constant percentage; not a constant amount (logorhythmic increase NOT linear increase)

Applying Weber’s Law If the cost of a pop is $.50 and it goes up by $0.50, it is very noticeable. If the cost of a television is $500 and it goes up by $0.50, it is not noticeable. BUT, if the cost of a pop went from $ .50 to $1.00, you could say that the price doubled to get the same increase in the cost of the tv, it would have to go from $500 to $1000 -------YIKES! .

Applying Weber’s Law In sales – sell the more expensive item first. Then accessories or add-ons don’t seem so bad (ie, buying satellite radio for your car. After agreeing to spend $20,000, an extra $500 a year doesn’t seem ridiculous).

Absolute threshold We sense only a sliver of the info coming at us. We can’t see everything (like X-rays or radio waves) or hear everything (the family dog can hear much more than us). Take sound for example, at some point there is a point where we can’t hear a frequency (but the dog still can). This cut-off point to sensation is called the absolute threshold.

Turn to the person beside you and say Weber’s law is the difference in percentage, NOT amount, when it comes to noticing a stimulus How high do YOU have to turn up the volume on your device to notice an actual difference?

Absolute threshold It’s defined as the minimum stimulation needed to detect light, a sound, a pressure, taste or odor 50% of the time. As an example, people lose the ability to hear high-pitched as they grow older. Mosquito Ring tone Experiment http://www.freemosquitoringtones.org/hearin g_test/