Studies into human visual perception rarely control for how participants weigh up processing speed against processing accuracy.  For instance some participants may emphasise fast responses but accept a high level of mistakes while others may be accurate but slower in responding.  This paper successfully utilized an experimental procedure which controls for the two factors and applied it to a well-known phenomenon, the Inhibition of Return (IOR)-effect.  The IOR-effect refers to empirical evidences that people find it difficult to attend to a location more than ones, i.e. the return of attention is inhibited. For the first time, the paper presents evidence in one experiment that IOR affects both, processing speed and processing accuracy.

It is also worth noting that this article is the result of an international collaboration with Raymond Klein at Dalhousie University, Halifax, Canada.


Inhibition of return (IOR) occurs when reaction times (RTs) are slowed to respond to a target that appears at a previously attended location. We used the speed–accuracy trade-off (SAT) procedure to obtain conjoint measures of IOR on sensitivity and processing speed by presenting targets at cued and uncued locations. The results showed that IOR is associated with both delays in processing speed and shifts in response criterion. When the target was briefly presented, the results supported a criterion shift account of IOR. However, when the target was presented until response, the evidence indicated that, in addition to a response bias effect, there was an increase in the minimal time required for information about the target to accumulate above chance level. A hybrid account of IOR is suggested that describes effects on both response bias and perceptual processing.


Zhao, Y., Heinke, D., Ivanoff, J., Klein, M. K. & Humphreys, G. W. (in press). Two components in IOR: Evidence for response bias and perceptual processing delays using the SAT methodology. Attention Perception & Psychophysics.
DOI 10.3758/s13414-011-0181-z