10.5 Semantic Memory Network Model
What Is Memory?
Have you ever had the experience of seeing something and suddenly remembering a different thing that is seemingly completely unrelated?
For example, Jane was driving past a farm one day. When she noticed the farm house, she suddenly remembered that her favorite sweater needed to go to the cleaners!
You might say, ”Well, that was random. Why would the farm house remind her of her dirty sweater?” That is the magic of memory!
Memory is simply the ability to retrieved stored information. How is memory stored? How are memories connected to each other?
This lesson reviews the network model theory of semantic memory storage.
Organization of Memory
Semantic memory refers to our memory of facts and information. This includes things like what a cat is and how to spell the word ”cat.” It is non-emotional, simply informational memory. Episodic memory, on the other hand, is our memory of specific actions or events in our life. It is easy to see how we remember important, emotional events, but how do we organize all the information we have been given over our lifetimes to retrieve that information efficiently later?
In the late 1960s, Allan Collins and Ross Quillian proposed that memory is organized in a set of nodes connected by links. The nodes are categorizations of information to which other nodes of information are connected.
Previously, we saw that Jane was looking at a farm. What might a network model of the memory of a farm look like?
Notice that the primary category in this network is ”FARM” and the memory organization shows smaller subcategories associated with a farm (machines, animals, crops). Each sub-node would have additional information. For example, the sheep node (connected to the animal node) might also connect to the following information:
OK, so memory is organized through groups of categorical information called nodes and their associated pieces of information. How does this help us figure out why Jane remembered her sweater after seeing a farm?
Priming is the term used to describe our minds’ getting information ready to be used. When we think of a node (like ”FARM”), we automatically prime (or get ready) all the information connected to that node. You can think of this as our own personal computer cache, the system in which a computer pulls the next bit of data off the hard drive in anticipation of the user requesting it next.
When Jane saw the farm, her internal memory network activated the node ”FARM,” which led to priming information about the machines on a farm, crops grown on a farm, and the animals found on farms. Thinking about the animals led her to the sheep, which primed information about sheep, including that they grow wool. Wool is a material used to make clothing, and sweaters are types of clothes that can be made from wool. Activating the node relating to sweaters would have automatically primed any information Jane had on her own sweater.
Thus, seeing the farm made Jane remember her sweater. The pathway of activation and priming can be visually represented like this:
We’ve seen that memory is organized by nodes linked together through some connections. We’ve followed the path of what seemed like an obscure connection to see the logical way in which the sight of one item led Jane to remember another.
But why do we sometimes have difficulty remembering some things, and why are other things so easy to remember? It depends on the strength of the connection between the pieces of information.
You can think of it a bit like a map of memory. Think of the nodes as the cities, the smaller bits of information as the small towns, and the links connecting them as the roads.
Some roads are wide, like six-lane highways. Cars can travel quickly and unimpeded down these roads from one place to another. Collin and Quillian would relate these roads to a strong connection. Two cities connected by a wide, smooth, short road allow for very quick access from one to the other. Similarly, two pieces of information that are connected very strongly allow for very fast priming of each other if either is activated.
Sometimes places are very distant or roads may be narrow and not well maintained. It isn’t easy to travel on roads like these. Likewise, when memories have a weak connection, it can take longer for your mind to travel across the connections to reach the information. This is why you wake up in the middle of the night suddenly remembering the answer to the question you thought you forgot earlier in the day. Your mind travels through the primed nodes as you go about your business; when it gets there, the information is activated, and you consciously remember it.
In the network model of semantic memory, there is really no such thing as forgetting; there is simply the inability to access stored information. Again, if you consider the highway metaphor for memory, when a bridge is washed out because of a flood, the town on the other side of the bridge is temporarily inaccessible. In the same way, if a node of information becomes too weakly connected to any other piece of information, it becomes inaccessible. Only when the link is strengthened (such as through study for academic pursuits) will the information be readily available.
Allan Collins and Ross Quillian developed the network model of semantic memory organization in the late 1960s. This network model indicates that nodes of information (categories) are connected to each other through strong and weak links. Priming allows for our memory to ready associated information for retrieval. In this model, forgetting is simply the inability to retrieve stored information. The information is still in memory; however, its links are just too weak to prime.