Do infants have the horizontal bias?
A robust set of studies show that adults make more horizontal than vertical and oblique saccades, while scanning real-world scenes. In this paper we study the horizontal bias in infants. The directions of eye movements were calculated for 41 infants (M=8.40 months, SD=3.74, range=3.48-15.47) and 47 adults (M=21.74 years, SD=4.54, range=17.89-39.84) while viewing 28 real-world scenes. Saccade directions were binned to study the proportion of saccades in the horizontal, vertical and oblique directions. In addition, saccade directions were also modeled using a mixture of Von Mises distributions, to account for the relatively large amount of variance in infants data. Horizontal bias was replicated in adults and also found in infants, using both the binning and Von Mises approach. Moreover, a developmental pattern was observed in which older infants are more precise in targeting their saccades than younger infants. That infants have a horizontal bias is important in understanding infants' eye movements. Future studies should account for the horizontal bias in their designs and analyses.
Department of Psychology, University of Amsterdam, Nieuwe Achtergracht 129-B, 1018 WT Amsterdam, The Netherlands; Research Priority Area Yield, University of Amsterdam, The Netherlands; Amsterdam Brain and Cognition, University of Amsterdam, The Netherlands. Electronic address: D.R.vanRenswoude@uva.nl.
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Van Renswoude
Department of Psychology, University of California, 1285 Franz Hall, Box 951563, Los Angeles, USA. Electronic address: Scott.Johnson@ucla.edu.
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Johnson
Department of Psychology, University of Amsterdam, Nieuwe Achtergracht 129-B, 1018 WT Amsterdam, The Netherlands; Department of Education and Child Studies, Leiden University, Pieter de la Court gebouw, Wassenaarseweg 52, 2333 AK Leiden, The Netherlands; Research Priority Area Yield, University of Amsterdam, The Netherlands; Amsterdam Brain and Cognition, University of Amsterdam, The Netherlands. Electronic address: M.E.J.Raijmakers@fsw.leidenuniv.nl.
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Raijmakers
Department of Psychology, University of Amsterdam, Nieuwe Achtergracht 129-B, 1018 WT Amsterdam, The Netherlands; Research Priority Area Yield, University of Amsterdam, The Netherlands; Amsterdam Brain and Cognition, University of Amsterdam, The Netherlands. Electronic address: I.Visser@uva.nl.
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Visser
D000293:Adolescent; D000328:Adult; D002657:Child Development; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D010775:Photic Stimulation; D012438:Saccades; D055815:Young Adult
Horizontal bias; Infant development; Infant eye movements; Saccade directions; Scene viewing