What is Associative Memory?

Associative memory is defined as the ability of a machine to learn and remember the relationship between unrelated items or entities.

There are two types of Associated Memory

(a). Hetero - Associated Memory

(b). Auto - Associated Memory

 

What is Hetero-Associative Memory?

The input and output patterns are difference, input patterns are the noisy or incomplete copy on stored information

Input (x) ≠ Output (y)

Telephone Directory is a example of Hetero-Associative Memory,  its contains name and phone number and both are two different  unrelated items.

Example:

Name	Phone Number
Mr. Firoj Bakhshi	+447405490000
Mrs. Nancy	+447788400000
Mr. Nikhil	+919700000000
Mr. Susheel Panchal	+919700000000

When directory is presented with the name it retrieves the corresponding phone number.

Mr. Firoz Bakhshi?    >>  +447405490000

What is Auto-Associative Memory?

The input and output patterns are identical, input patterns are the noisy or incomplete copy on stored information

Auto – Associative Memory is specialised in pattern recognition & completion.

Input (x) = Output (y)

Search some fragment of text on Google it retrieve the whole word

Example:

 

Coexistence of Auto & Hetero – Associative Memory, Face recognition has both the components, the face completion is Auto-Associative Memory and getting the name of person is Hetero- Associative Memory. Remember a number of faces, but we can recognize the face by just a small part of it is visible and output is with complete face and name “Rajnikanth”.

What are the properties of Associative Memory?

• Content Addressable (similar to the standard computer memory)
• It is insensitive to small errors in the input patterns (noise resistance)
• It is insensitive to removal of network connections and units (graceful degradation: it is the ability of a computer, machine, electronic system or network to maintain limited functionality even when a large portion of it has been destroyed or rendered inoperative).
• It is highly capable of parallel processing of the information

  

Difference with the Human Brain:

Associative Memory, Usually there is a separate Learning Phase (when the associations are stored), and a Recall Phase (when the stored information is retrieved).

Typesof Associative Memory Model.