Lexical decision, visual hemifield and angle of orientation

Area of Science:

• Cognitive Psychology
• Neuroscience
• Psycholinguistics

Background:

• The visual hemifield presentation of stimuli is a common paradigm in cognitive neuroscience.
• Right visual field (RVF) superiority for processing linguistic stimuli has been consistently reported.
• The influence of stimulus orientation on visual field asymmetries is less understood.

Purpose of the Study:

• To investigate how varying stimulus orientation affects lexical decision performance.
• To determine the role of stimulus orientation in right visual field (RVF) superiority.
• To examine the impact of orientation on response bias and accuracy in visual hemifield tasks.

Main Methods:

• Participants performed a lexical decision task with word and nonword stimuli.
• Stimuli were presented at various orientations (0 to 90 degrees) in either the left or right visual field.
• Reaction time (RT), accuracy, discrimination ability (d'), and response bias (log beta) were measured.

Main Results:

• Increasing stimulus orientation from 0 to 90 degrees led to increased RT and decreased accuracy and d'.
• RVF superiority in discrimination (d') was observed across all orientations.
• RVF superiority in RT and a bias to respond 'word' were significant only at 0 and 15 degrees, requiring horizontal presentation.

Conclusions:

• Horizontal stimulus orientation is crucial for observing RVF superiority in processing speed and response bias for words.
• RVF superiority in discriminating words from nonwords is orientation-independent.
• These findings highlight the complex interplay between visual field, stimulus orientation, and cognitive processing of linguistic information.