Reference: Green, J. J., Spalek, T. M., & McDonald, J. J. (2020). From alternation to repetition: Spatial attention biases contribute to sequential effects in a choice reaction-time task. Cognitive Neuroscience, 11(1–2), 24–36.

Every day you go to watch TV, the remote has been right there, on the couch…but today, it’s not there. You sit frustrated on the floor staring at the couch you have repeatedly torn apart and put back together. 

Now contrast the above scenario with the following; you are building a Lego set and a large pile of pieces are strewn about in front of you. Your eyes scan from piece to piece until you finally find the one you need.

Without the expectations of where an item will be, your attention effortlessly moves from item to item. This behavior is supported by a phenomenon called inhibition of return. Inhibition of return causes a person’s attention to be biased away from recently attended locations (1), which explains why people are slower to find a target item at repeat locations (2,3). Indeed, searching a couch or any location after you already looked there would be counterproductive. This usually beneficial mechanism is considered by many researchers as a fundamental way attention operates in the brain. For example, the effect persists regardless of a person’s conscious efforts to attend to the location again (4). Why then do people have this love-hate relationship with their voracious couch cushions? 

The mundane frustration is likely caused by multiple factors that can exist at a larger scale than the subsecond effects of inhibition of return. For example, people live in a (hopefully) sane world and will have explicit expectations that items associated with an action (e.g., the TV remote) are going to be near other items associated with that action (e.g., the couch you sit on to watch TV). Another factor is expectations driven by experience. TV remotes are frequently found in or around the couch so people are usually rewarded for their couch cushion spelunking efforts. These past experiences of finding an item at a particular location can implicitly bias visual search (5). You likely experienced this bias if you ever tried to use a favorite website or application after a redesign and found yourself exclaiming, “WHAT! The menu button is no longer in the top right corner! How dare they!” Clearly expectations can produce vehement responses, but can they also overcome the power of inhibition of return?

This image was created for this blog. See Jessica Green’s paper for the official methods

Researcher Jessica Green and colleagues at Simon Fraser University in Canada recently investigated this question by measuring the presence of inhibition of return when viewing a series of searches. Participants were shown two circles on a computer screen and asked to indicate if a target color appeared at the left or right circle. Like the couch example, explicit knowledge can also affect search behavior. To control for explicit knowledge, the target was equally likely to repeat or change locations, e.g right/right, right/left, etc. Embedded in the task were sequences consisting of 5 searches where the target appeared in the same location 5 times in a row, e.g. left, left, left, left, left. The researchers found that at the beginning of the sequence, participants were slower to detect targets in repeat locations, a classic sign of inhibition of return. But by the 5th item in the sequence, participants were faster to detect targets in the repeat location, a reversal of inhibition of return!

A common criticism of expectation effects is that they are due to motor response bias rather than an attentional bias. With only reaction time data, the faster reaction time could be because the participant was biased to click the repeat mouse button or because the participant was biased to attend to the repeat location. To counter this issue, the researchers also measured electrical activity in the participant’s brains. Using an EEG (electroencephalogram) they measured a neural signature of selective attention called the N2pc. The researchers found that changes in the N2pc aligned with changes in reaction time. At the beginning of the 5 search sequence, the N2pc indicated inhibition of return. But at the end of the 5 search sequence, the N2pc indicated that attention was now biased toward the repeat location. These results suggest that the location expectation was not merely a muscle memory but impacted how people attended to the display. Rather than being biased away from where they just looked (i.e., inhibition of return), people were now biased to look at the location again.

This study, and a growing body of research, shows that our attention can be biased by past experiences. As someone who lives with an eccentric husband and an active cat, I have learned to look for objects in unusual locations. Sometimes my husband decides the top of the fridge is the best place to quickly set something down and the remote is in the freezer because it fell in when the door was opened. Other times the remote is on the complete other side of the room under the entertainment center because my cat decided the small lightweight Apple TV remote was a spectacular cat toy. But the next time you are digging through your couch, you can reassure yourself that the reason you are searching there again — even though you already looked — is likely because of all the previous times you found the remote there.

Additional References:

1. Pierce, A. M., Crouse, M. D., & Green, J. J. (2017). Evidence for an attentional component of inhibition of return in visual search. Psychophysiology, 54(11), 1676–1685.
2. Posner, M. I., & Cohen, Y. A. (1984). Components of visual orienting. In H. Bouma & D. G. Bouwhuis (Eds.), At- tention and performance X (lip. 531-556). Hillsdale, NJ: Erlbaum.
3. Klein, R. (1988). Inhibitory tagging system facilitates visual search. Nature, 334 , 430-431.
4. Berlucchi, G., Chelazzi, L., & Tassinari, G. (2000). Volitional covert orienting to a peripheral cue does not suppress cue-induced inhibition of return. Journal of Cognitive Neuroscience, 12(4), 648–663.
5. Awh, E., Belopolsky, A. V., & Theeuwes, J. (2012). Top-down versus bottom-up attentional control: A failed theoretical dichotomy. Trends in Cognitive Sciences, 16(8), 437–443.