Edgren Scholars Part 1 of 4

by Steffanie Lindgren ’10

Professor of Psychology Adam Johnson and Bethel senior Zach Varberg

How do we go back and fill in the blanks of an incomplete memory? This is one of the questions that Professor of Psychology Adam Johnson and senior computer science major Zach Varberg sought to answer in their research as summer Edgren scholars.

The Edgren Scholars Program is a significant opportunity for collaborative research between faculty and students. Faculty participates in mentoring highly motivated students to levels of professional skill usually difficult to attain during the school year. Almost all students who participate in summer research continue on to graduate school.

Johnson explained his research topic: “Constructed memory means that memories are constructed from what we know rather than perfectly retrieved from a pristine keeping place. Constructive memory functions in much the same way that an artist would draw a picture. The artist begins with a general sketch and then begins to fill in segments in richer detail as they go,”

The memory we have enables us to go back as well as forward in time. For example, the ability to vividly remember a birthday from many years ago also allows us to picture what a birthday would be like in the future. This is called episodic memory, the personal memories of whole events in a person’s life.

Episodic future thinking involves imagining an episode that will exist in the future in order to create a plan for the future. Johnson and Varberg looked at whether rats demonstrate episodic future thinking. Typically, animals are thought to only have thoughts about immediate needs. For, example, if they feel hungry, they think about eating.

Johnson and Varberg used existing research on reinforcement learning in rats to develop computational models for when animals don’t follow this immediate-need pattern. If a rat stops on his way to eat a piece of cheese, he is not acting on his immediate need. Why did he stop?

In addition to their work with memory, Johnson and Varberg drew from research about how we process a visual rotation. If we see an object, such as a stuffed mouse, in an upright position and then upside down, our minds must mentally rotate 180 degrees. Therefore, if the mouse was in an upright position and then only slightly rotated, we would be able to process the change more quickly.

Because their area of research is relatively unexplored, Johnson and Varberg must develop the vocabulary to describe the processes and results of their research. “For me, one of the most exciting things was trying to answer a question that nobody knows the answer to,” said Varberg.

As a result of their research, Johnson and Varberg are closing in on a mathematical model of imagination that will allow them to understand what constructed memories are and how they contribute to behavior. Johnson and Varberg’s research is ongoing.