What do you know, and why do you know it?

What you know, but don’t know you know, affects you more than you know, suggests Larry Jacoby, Ph.D., professor of psychology in Arts & Sciences.

“Memory plays a very powerful role in how we see and interpret the world, even in situations where we are completely unaware of the events that gave rise to these memories,” says Jacoby, a leading expert on the power of unconscious and automatic forms of memory.

In nearly three decades of research into the foibles of human memory, Jacoby has made pioneering contributions to our understanding of how various forms of memory are processed in the human mind.

His work has shown how cognitive declines associated with normal aging leave older adults especially vulnerable to telemarketing scams and other cons that prey on a victim’s faltering memory skills.

His studies even shed light on why it’s difficult for some of us to avoid telling the same boring stories over and over again, especially to people who have heard them all before. He shows why we’re more likely to retell an old joke to the very person who told it to us in the first place.

Much of his research is based on a theory he helped develop, the notion that memory consists of two separate processes — an automatic process, known as familiarity, and a consciously-controlled process often referred to as recollection.

“Jacoby has come up with some ingenious methods of separating out how these two processes — familiarity and recollection — influence memory,” says Gus Craik, Ph.D., a longtime colleague of Jacoby and senior scientist at the Rotman Research Institute in Toronto.

“He’s always been extremely creative in his approach. He really has taken the study of memory and cognition in a number of new directions. He’s clearly among the top few contributors to the theoretical understanding of how human memory works.”

Jacoby’s rise to the top tier of cognitive science was never a certainty. He began psychology studies at Washburn University in Topeka, Kansas, a lackluster student with a passion for football and strong drink.

“I played college football in an era when 220 pounds was still big enough to play in the line,” says Jacoby, a former center on offense and tackle-guard on defense. “As an undergraduate, my academics were not what you would call strong.”

His spent his childhood in Smileyburg, Kansas, where his father ran a service station that also served as a makeshift tavern and auto repair shop. “The town was so small,” he jokes, “that the population dropped by 20 percent when our family moved out.”

His father relocated the family to Wichita and found work in the oilfields. Jacoby spent summers working alongside him — digging ditches, throwing pipe and operating heavy machinery for $1.50 an hour.

“It was good conditioning for football, but back-breaking enough that there was no way I wanted to spend my life working in an oilfield,” he recalls.

At Washburn, Jacoby met his future wife, Carole, whom he credits with curbing his enthusiasm for Jack Daniels and other bad influences. His academic priorities changed when he took a course on animal learning and began assisting a professor with a rat-maze experiment. Hooked on science, his grades improved enough to squeeze into the psychology graduate program at Southern Illinois University, Carbondale.

“I eventually realized I didn’t care that much about rats,” he recalls. “I started to get more and more interested in memory, especially human memory.”

After earning a doctoral degree in psychology, he took his first faculty job at Iowa State University. In 1975, he moved to McMaster University in Canada, where he would remain off-and-on for much of the next 25 years.

Following stints at the University of Texas, University of Utah and New York University, he passed up an offer from Yale, choosing instead to join memory experts here in 2000.

“I’m very excited to be working with these people,” says Jacoby, running through a list of colleagues with strengths in behavioral cognition and neural imaging. “Washington University has an incredibly strong program in memory studies. It can make a real claim to having the strongest memory group in North America, if not the world. This is as good as it gets.”

“The environment here is extremely collegial. People are nice and they actually talk to each other,” he says. “I also like our students. They’re bright, enthusiastic, good kids. I enjoy working with the undergraduates in my lab.”

Not shy about poking fun at himself in the classroom, he’s a star on a student Web site that chronicles some of the more colorful comments from faculty lectures.

“It’s just so pretty,” he exclaims, during an animated discussion of Shepard’s mental rotation results. “Nature might screw around, but it doesn’t screw around with data that pretty!”

Jacoby’s checkered undergraduate career gives him an advantage, he says, in counseling students facing troubles of their own.

“I study things that relate to everyday experiences, so it’s nice to have led a life where you’ve had some experiences of your own,” he quips. “I’m amazed by students who come in here with their entire lives planned out in advance. I tell them not to worry if things don’t go exactly as expected.”

And, as Jacoby’s experiments have shown, even reality is not always what it seems. In a current study with psychology graduate student Chad Rogers and other colleagues, he is exploring age differences in the subjective experience of hearing and seeing.

“Older adults,” he explains, “are more likely to claim to say they ‘hear’ things that were not actually said but were expected. This age difference in the subjective experience of hearing is important for applied concerns.

As an example, when fitting hearing aids only the objective ability to discriminate among auditory stimuli is tested. However, it is equally important to test subjective experience. The subjective experience of hearing is important because we act on that subjective experience.”

Jacoby’s experiments often involve some subterfuge that encourages participants to focus on one stream of information while another secondary stream hums softly in the background or flashes momentarily across a computer screen. He shows that the mind is capable of retaining information from these secondary or “unattended” streams, even when we have little or no recollection of being exposed to them.

His current research focuses on age-related cognitive declines.

His studies demonstrate that many memory problems associated with aging can be tied to declines in higher-level conscious memory processes, while more automatic forms of memory remain largely unaffected by aging.

To understand these differing forms of memory, consider what happens when you spot a familiar face. Automatic memory helps you recognize the face as familiar, but figuring out this person’s name or where you know them from requires the second, more difficult, conscious memory process known as recollection.

As aging degrades conscious memory and recollection skills, the more automatic memory processes work unopposed. It is the unopposed automatic influences of memory that are responsible for the older adults’ unwanted retelling of stories, retelling of jokes to the very person from whom they heard the jokes.

“These automatic influences of memory can mislead the elderly person and make them mistakenly think that they remember something that actually didn’t happen,” says Jacoby. “What’s more, our studies show that older adults often are extremely confident about the accuracy of things they think they remember. They’re more likely to make mistakes, and more difficult to convince they’re wrong.”

In recent work, Jacoby and colleagues have shown that repeated training over short intervals can help older adults improve their recollection skills. The findings hold promise for helping seniors cope with a wide range of practical challenges, such as remembering to take regular medications.

As far as his own future, Jacoby has no plans to retire in the near future. His wife, following a long career in education, now works side-by-side with him in his research lab, coordinating grant applications and interactions with study participants.

“We do a lot of bicycling and recently took a vacation to Mexico for some snorkeling,” he says. “In March, we are headed to Lisbon in Portugal for me to talk about my research, and plan to do some traveling around Europe afterward.”