Asymmetrical effects of adaptation to left- and right-shifting prisms depends on pre-existing attentional biases.
Proposals that adaptation with left-shifting prisms induces neglect-like symptoms in normal individuals rely on a dissociation between the postadaptation performance of individuals trained with left- versus right-shifting prisms (e.g., Colent, Pisella, & Rossetti, 2000). A potential problem with this evidence is that normal young adults have an a priori leftward bias (e.g., Jewell & McCourt, 2000). In Experiment 1, we compared the line bisection performance of young adults to that of aged adults, who as a group may lack a leftward bias in line bisection. Participants trained with both left- and right-shifting prisms. Consistent with our hypothesis, while young adults demonstrated aftereffects for left, but not right prisms, aged adults demonstrated reliable aftereffects for both prisms. In Experiment 2, we recruited a larger sample of young adults, some of whom were right-biased at baseline. We observed an interaction between baseline bias and prism-shift, consistent with the results of Experiment 1: Left-biased individuals showed a reduced aftereffect when training with right-shifting prisms and right-biased individuals showed a reduced aftereffect when training with left-shifting prisms. These results suggest that previous failures to find generalizable aftereffects with right-shifting prisms may be driven by participants' baseline biases rather than specific effects of the prism itself.
Goedert
Kelly M
KM
Department of Psychology, Seton Hall University, South Orange, New Jersey 07079, USA. kelly.goedert@shu.edu
Leblanc
Andrew
A
Tsai
Sen-Wei
SW
Barrett
Anna M
AM
D000222:Adaptation, Physiological / Q000502:physiology*; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001288:Attention / Q000502:physiology*; D015982:Bias; D023882:Dominance, Ocular / Q000502:physiology*; D005260:Female; D005366:Figural Aftereffect / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009048:Motor Skills / Q000502:physiology; D010775:Photic Stimulation / Q000379:methods; D011601:Psychophysics; D014794:Visual Fields / Q000502:physiology; D014796:Visual Perception; D055815:Young Adult