With a well-established, 25-year academic career at the University of Toronto, Colin MacLeod made a surprising change in 2003 by joining the cognitive area in the University of Waterloo’s Department of Psychology.

“U of T was a great place to be and I would have happily spent my entire career there, had I not met Ramona,” says MacLeod, “It’s been a very productive and happy 15 years.” Ramona Bobocel, MacLeod’s partner and colleague, is also a Waterloo psychology professor.

A key to that happiness is surely the boundless interest MacLeod takes in his research and teaching in cognitive psychology, specifically in his areas of attention, learning, and memory. And perhaps administrative leadership is part of it too, as MacLeod will soon complete a seven-year tenure as chair of one of Canada’s largest and most productive psychology departments.

This month, MacLeod is receiving the highest honour from the Canadian Psychological Association with the presentation of its Gold Medal Award for Distinguished Lifetime Contributions to Canadian Psychology. The award celebrates outstanding Canadian psychologists who have dedicated their careers to advancing the field nationally and globally.

Receiving a lifetime achievement award, however, does not necessarily mean that MacLeod is retiring from the lab and classroom any time soon. “I always feel that getting up and going to work is a privilege,” he says. “How can you not be interested in memory?” 

During his undergraduate years at McGill University, MacLeod developed an accidental interest in the workings of memory. At the time, he thought he would like to work in radio given his diehard music fandom and encyclopedic memory for songs and artists. “Memory was of interest to me partly because of the music: I would hear two notes of any song and could name the artist and title. I think that’s what eventually led me to an interest in memory and attention.”

Memory is reconstructive, he explains, pointing out that people often mistakenly think of it as a non-stop narrative or video of our world. “It’s far from that,” he says. In fact, we are constantly reconstructing little bits of memory from our world with cues. Like when witnesses revisit the scene of a crime: revisiting a certain location helps to retrieve a particular experience as a memory.

“Memory is this abstracting device that pulls stuff out of the world, but once you’ve got it you often don’t necessarily know where you got it from,” say MacLeod. “You don’t know what other memories have intruded into it. It is what it is, and this has led to all kinds of interesting issues in memory research.”

The field of cognitive psychology has grown in parallel with MacLeod’s career — his doctoral supervisors were among its pioneers. In contrast to the older field of behavioural psychology, “cognitive research recognizes that there is a lot of the individual involved, there’s a lot more to it,” says MacLeod. The field not only offers significant insights on human learning, but also contributes to the development of machine learning and artificial intelligence. “I picked a good one,” he says.

As a researcher, MacLeod is well known for his discovery of the production effect —the simple yet powerful idea that we can remember something best if we say it aloud. However, to his own bemusement, he is most famous in psychology for his 1991 paper on the Stroop effect. “I’ve published 15 papers with students and colleagues on my production effect research and maybe half a dozen on the Stroop effect. But I’m way better known for the Stroop effect work,” he says. With more than 5,000 citations to date, his Stroop paper is one of the most cited papers in psychology research worldwide in the last 50 years.

The Stroop effect happens when some form of interference derails attention. Distraction is part of daily life, especially these days, so the Stroop effect is ubiquitous in psychology as an influential model for testing attention capacity and processing speed. Because MacLeod’s paper is a comprehensive review of Stroop effect research since the 1930s, it has become the definitive reference on the subject.

While his famous paper has indeed affected MacLeod’s academic capital, he is most excited about his own research discoveries. After all, he explains, the Stroop test can tell us about how we function cognitively, but the production effect can help improve our cognition: it gives us a tool we can all use.

“When we add an active measure, or a production element, to a word or concept, it becomes more distinct; our mind encodes it more distinctly for long-term memory,” explains MacLeod. It’s like the experience of navigating a new route in a car as either passenger or driver; the passenger is relatively passive and may not encode the route for the return trip but when the driver retraces the route, she will have better recall because of her active engagement in navigating the original route.

Testing different modes of the production effect, MacLeod and his research partners —often graduate students and postdoctoral fellows— discovered that saying it out loud makes the most substantial improvement in learning. In one simple test, for example, university students were instructed to read passages from a textbook, some aloud and some silently. When the students came back to the lab a week later to be tested on their memory of the readings, they could remember significantly more from the passages read aloud.

MacLeod and postdoctoral fellow, Noah Forrin, recently co-authored a paper, This time it’s personal: The memory benefit of hearing oneself. It garnered close to 50 media interviews between the two of them, attesting to the everyday relevance of their research findings.

Asked about a research bucket list, MacLeod names and describes in colourful detail new studies that include contingency learning, which is how we make connections between things we learn, and directed forgetting, which can help people with post-traumatic distress. Certainly, his fascination with attention, learning, and memory is contagious — as he said, How can you not be interested?

Along with his new Gold Medal Award, MacLeod holds the Donald O. Hebb Distinguished Contribution Award from the Canadian Society for Brain, Behaviour, and Cognitive Science and the Donald O. Hebb Award for Distinguished Contributions to Psychology as a Science from the Canadian Psychological Association. In 2016, MacLeod was elected Fellow of the Royal Society of Canada.