‘Alternate-goal bias’ in antisaccades and the influence of expectation
- 128 Downloads
Saccadic performance depends on the requirements of the current trial, but also may be influenced by other trials in the same experiment. This effect of trial context has been investigated most for saccadic error rate and reaction time but seldom for the positional accuracy of saccadic landing points. We investigated whether the direction of saccades towards one goal is affected by the location of a second goal used in other trials in the same experimental block. In our first experiment, landing points (‘endpoints’) of antisaccades but not prosaccades were shifted towards the location of the alternate goal. This spatial bias decreased with increasing angular separation between the current and alternative goals. In a second experiment, we explored whether expectancy about the goal location was responsible for the biasing of the saccadic endpoint. For this, we used a condition where the saccadic goal randomly changed from one trial to the next between locations on, above or below the horizontal meridian. We modulated the prior probability of the alternate-goal location by showing cues prior to stimulus onset. The results showed that expectation about the possible positions of the saccadic goal is sufficient to bias saccadic endpoints and can account for at least part of this phenomenon of ‘alternate-goal bias’.
KeywordsAntisaccade Prosaccade Direction Global effect History Probability
This work was supported by CIHR operating grant MOP-81270. MA was supported by a grant from the Schweizerische Stiftung für medizinisch-biologische Stipendien and the Swiss National Science Foundation and JB by a Canada Research Chair and a Senior Scholar award from the Michael Smith Foundation for Health Research.
- Everling S, Munoz DP (2000) Neuronal correlates for preparatory set associated with pro-saccades and anti-saccades in the primate frontal eye field. J Neuriosci 20:387–400Google Scholar
- Findlay JM, Blythe HI (2009) Saccade target selection: do distractors affect saccade accuracy? Vision Res 49:1267–1274Google Scholar
- Lee H, Abegg M, Rodriguez A, Koehn J, Barton JJ (2010) Why do humans make antisaccade errors? Exp Brain Res 201: 65–73Google Scholar
- Lévy-Schoen A (1969) Determination et latence de la response oculomotrice a deux stimulus. L′Anee Psychol 74:43–66Google Scholar
- Polli F, Barton J, Vangel M, Goff D, Iguchi L, Manoach D (2006) Schizophrenia patients show intact immediate error-related performance adjustments on an antisaccade task. Schizophrenia Res 82:191–201Google Scholar
- Reuter B, Philipp A, Koch I, Kathmann N (2006) Effects of switching between leftward and rightward pro- and antisaccades. Biological Psychology 40:122–130Google Scholar