13 October 2013

ATTENTION: Flicker paradigm

Change blindness refers to the inability to see a change in a scene, in other words, not noticing that an image has been altered. Research has shown that people only see changes when they expect them, if not we don’t realize they have happened. The reasons these changes usually remain unnoticed by the observer include obstructions in the visual field, eye movements, or a lack of attention. Many researches have studied change blindness before (e.g. Bridgeman, Hendry, & Stark, 1975; French, 1953; Friedman, 1979; Hochberg, 1986; Kuleshov, 1987; McConkie & Zola, 1979; Pashler, 1988; Phillips, 1974).

A common way of testing change blindness is the flicker paradigm (e.g. Simons, D. J., & Rensink, R. A., 2005), which consists in a black screen (flicker) presented in between an image and the altered form of that image and asking the participant to report any changes in the picture. Our aim is to investigate the flicker paradigm, altering the time the flicker is presented and seeing how change blindness is altered because of this. Our prediction is that the longer the time of the flicker the more change blindness there will be (the subject will see less changes).

Simons, D. J. (2000) studied the current approaches to change blindness affirming how people are surprisingly poor at noticing large changes to objects, photographs, and motion pictures from one instant to the next. He discovered five different explanations for change blindness: overwriting (the initial representation is simply overwritten or replaced by the blank interval or by the subsequent image); first impressions (observers accurately encode the features of the initial object or scene and then fail to encode the details of the changed scene); nothing is stored (nothing about the visual world is stored internally. Only information that has been abstracted from the percept will be retained once the image or scene is gone.); everything is stored but nothing is compared (people can firmly hold two beliefs without realizing that they are fundamentally contradictory); and feature combination (two consecutive views are overlain and combined. Some features and objects might be retained from the first view and others might be retained from the second view). We want to analyse this conclusions to see which one can explain our experiment best or if none of the above give an explanation to it. 

Further investigation (e.g. Simons, D. J., Franconeri, S. L., & Reimer, R. L., 2000) achieved the conclusion that there is no difference in change blindness between having a flicker or not. Other authors (e.g. O'Regan, J. K., Rensink, R. A., & Clark, J. J., 1999) believe that change blindness occurs only in minor features in the environment, in other words, only central-interest changes are realized, as the subject does not pay any attention to minor details. This again proves that using a flicker or an interference will not alter the number of changes seen by the subject. 


  1. How interesting! and also very well explained. I could never imagine how this tipe of blindness occur. Congratulations for the blog!

    1. Thank you Regina!
      I will soon post more surprising things about psychology!