Sensory Memory contains information received immediately from a person's senses into the human brain.
Sensory information is stored
for just an instant in sensory
registers in the brain and is relatively unprocessed. While this information
is stored in our sensory memory, we decide which information is worth further
processing (Matlin, 1998, pp. 105-106).
The sensory memory discussed here is different from the memory of the senses, which may well be stored in long term memory.
Examples:
- You lose concentration in class during a lecture. Suddenly you hear a significant word and return your focus to the lecture. You should be able to remember what was said just before the key word since it is in your sensory register.
- Your ability to see motion can be attributed to sensory memory. An image previously seen must be stored long enough to compare to the new image. Visual processing in the brain works like watching a cartoon -- you see one frame at a time.
- If someone is reading to you, you must be able to remember the words at the beginning of a sentence in order to understand the sentence as a whole. These words are held in a relatively unprocessed sensory memory.
Capacity
Your brain can take in a lot of information fairly accurately, but this information is not processed much at all, and it does not remain in sensory memory very long. Exactly how long information can be stored in sensory memory differs according to source of the sensory information being remembered:
- iconic memory (visual sensory memory) - less than one second
- echoic memory (auditory sensory memory) - less than four seconds
Although sensory memory can occur for any of the senses, most sensory memory research seems to focus on iconic memory and echoic memory. Research into olfactory, tactile, and taste memories is less common.
What happens next?
Our brain must quickly decide what information will be processed enough to remain in short term memory and what information will be discarded. Less than 99 percent of sensory information is passed on to short term memory (Class Discussion, Psychology 2000). Two encoding processes by which we transfer information from sensory to short term memory are selective attention and feature extraction.
- Selective attention occurs when we notice important information necessary to meet our basic needs or our own interests.
- Feature extraction would be observing things as unusual, or "out of the ordinary."
Visual Sensory Memory Demonstration
Instructions: Hold your hand up in front of your face and wave it up and down.
Questions: What do you observe? Is this different from what you expected? If so, how?
Discussion:
You are able to see where your hand was before you moved it, so it looks like you have more than five fingers. Your eyes are taking in the new image of where the hand has moved to while your visual sensory memory allows you to still see where the hand was just an instant before.
Visual Sensory Memory Demonstration #2
Instructions: Take an index card cut a slit about 1/8th of an inch wide. Open an unfamiliar picture book and place the index card over a picture before looking at it. Now looking through the slit of the index card. Slide the card over the illustration. Guess what the picture is. Pick up the index card.
Were you right? How did you make your guess?
