Sensory Memory - Characteristics

Characteristics

SM is considered to be outside of cognitive control and is instead an automatic response. The information represented in SM is the "raw data" which provides a snapshot of a person's overall sensory experience. Common features between each sensory modality have been identified; however, as experimental techniques advance, exceptions and additions to these general characteristics will surely evolve. The auditory store, echoic memory, for example, has been shown to have a temporal characteristic in which the timing and tempo of a presented stimulus affects transfer into more stable forms of memory. Four common features have been identified for all forms of SM:

1. The formation of a SM trace is independent of attention to the stimulus.
2. The information stored in SM is modality specific. This means for example, that echoic memory is for the exclusive storage of auditory information, and haptic memory is for the exclusive storage of tactile information.
3. Each SM store represents an immense amount of detail resulting in very high resolution of information.
4. Each SM store is very brief and lasts a very short period of time. Once the SM trace has decayed or is replaced by a new memory, the information stored is no longer accessible and is ultimately lost. All SM stores have slightly different durations which is discussed in more detail on their respective pages.

It is widely accepted that all forms of SM are very brief in duration; however, the approximated duration of each memory store is not static. Iconic memory for example has an average duration of 500 ms which tends to decrease with age. The SM is made up of spatial or categorical stores of different kinds of information, each subject to different rates of information processing and decay. Genetics also play a role in SM capacity; mutations to the brain-derived neurotrophic factor (BDNF), a nerve growth factor, and N-methyl-D-aspartate (NMDA) receptors, responsible for synaptic plasticity, decrease iconic and echoic memory capacities respectively.