in collaboration with Michael Spivey, Natasha Kirkham and Merrit Hoover

Press play, watch the small movie to your right and answer the question posed at the end. Where you do think you were looking as you gave your answer? In a range of experiments, we have found that adults are roughly twice as likely to look at the square that contained the cross that was spinning while they heard the original information. Why would people look at a completely blank region of space when trying to recall something? We have found that it does not improve their memory if they look or not. More, surprisingly, in similar circumstances, infants as young as six months of age will have very similar looking behaviour. The Hollywood Squares and Baby Squares projects are our attempt to explain this intriguing behaviour, which we term dynamic spatial indexing of multi-modal events, or simply spatial indexing.

We have studied spatial indexing by tracking the eye movements of participants, examining under what circumstances they re-fixate locations associated with certain objects or events. This methodology has the advantage of allowing us to investigate the role of spatial indexing behaviour in adults, when they are engaged in a non-spatial task, and using the same paradigm, to measure spatial indexing in very young infants who are still learning about locations and objects.

In the movie to the left, you can see a subject being eye tracked in the first Hollywood squares experiment. First you'll see them watching a talking head, who is telling them a fact. After watching three more facts, the subject is then asked about the fact that had previously been presented in the top left location (circled in red). Observe their eye movements while answering.

The fact that people will systematically look at blank, unhelpful locations in spaces raises some interesting theoretical questions. For example, what attentional mechanisms support the spatial indexing? Do spatial indexes point towards objects in the world, locations, or sets of visual features? There is evidence that attention can be directed towards objects that are constrained by spatiotemporal properties (for a review see Scholl, 2001). In our latest work (Hoover & Richardson, 2008) we investigated whether spatial indexes attached to objects that are defined in this way. Rather than talking heads or spinning crosses, participants looked at cartoon animals while they heard pieces of factual information. For example, a white rabbit emerged from a mound of earth in one location while the participants heard a fact about Cleopatra. Later, an identical rabbit emerged from a second mound of earth but no fact was heard. In one condition, an animation of underground burrowing connected these two mounds; in another, the burrowing began from a different, off-screen location. The same object features are seen for the same amount of time across conditions. Spatiotemporal constraints alone imply that in the first case, the same white rabbit is seen in two locations, but in the second case, two visually identical but numerically distinct rabbits are seen. Our central question was: where will participants look when they are asked a question about Cleopatra? You can watch example eye movement recordings from the two conditions. We found that participants ignore the visually identical but numerically distinct rabbit, demonstrating that non-visual information is attached to spatiotemporally constrained objects in the world, not simply associated with co-occurring appearances and locations.

The ability to encode object locations, bind object properties and track them through space would be very useful for a developing infant learning about the world. We investigated whether six-month-old infants had access to spatial indexing mechanisms (Richardson & Kirkham, 2004). Rather than present infants with bits of factual information, we presented them with toys that danced around to a particular sound. After watching each toy dance three times, the squares moved round, and the infant heard one of the sounds while looking at the blank screen. In the movie shown here, you can see if the infant looked at the empty square that had previously contained the toy.

To learn more about the first set of Hollywood Squares experiments, you can download:

Richardson, D. C. & Spivey, M. J. (2000). Representation, space and Hollywood Squares: Looking at things that aren't there anymore. Cognition, 76, 269-295.

To learn more about the infant experiments and later adult studies on dynamic spatial indexing, you can view infant stimuli and eye movement recordings, or download:

Richardson, D. C. & Kirkham, N.Z. (2004). Multi-modal events and moving locations: Eye movements of adults and 6-month-olds reveal dynamic spatial indexing. Journal of Experimental Psychology: General, 133, 46-62.

Our latest research investigating the role of spatiotemporal object constraints is explained in this paper

Hoover, M. A. & Richardson, D. C. (2008) When Facts Go Down the Rabbit Hole: Contrasting Features and Objecthood as Indexes to Memory, Cognition 108(2), 533-42

A recent opinion paper in Trends in Cognitive Science was very critical of our explanation of these phenomena and proposed their own account. We were puzzled, because their account seemed nearly identical to ours. In fact, we felt that they misrepresented our views and the data in order to make their case. Read our reply to their piece in

Richardson, D.C., Altmann, G.T.M., Spivey, M.J., & Hoover, M.A. (2009) Much Ado About Eye Movements to Nothing: A reply to “Taking a new look at looking at nothing” by Ferreira, Apel & Henderson. Trends in Cognitive Science, 13, 235-236