Introduction

You are busily writing notes while your professor is lecturing when you realize that, although you know your professor was speaking, you have no idea what she just said. Why is this? Human cognition is capacity limited and we are often presented with more stimuli than we can process. We select some stimuli using attention and ignore others. In the note taking example, attention was being given to maintain what the professor had just said in short term memory, and so was not available to process the professor’s subsequent comments. The limited nature of attention and the way in which we switch between tasks has long been of interest to psychologists.

The present experiment explores how attention cannot be switched to a new stimulus while it is still being used to process a previous stimulus. Using the attentional blink paradigm, stimuli are presented one at a time for just 100 ms each. The participant’s task is to observe the stream and determine whether specific target stimuli are presented to them. The general finding is that participants are unable to identify a target if it is presented too soon after another target... it is as though the participant ‘blinked’ their eyes and missed it. The attentional blink usually lasts for up to 550 ms, after which time normal processing capacity resumes. Five hundred and fifty milliseconds may not seem like a long time, but it is long enough to prevent the detection of words, flashing visual signals, and some sounds. If you occupy yourself with several consecutive tasks, such as taking notes, you may miss entire sentences the professor says without noticing.