Effects of stimulus font and size on masked repetition priming: An event-related potentials (ERP) investigation

Abstract

The size and font of target words were manipulated in a masked repetition priming paradigm with ERP recordings. Repetition priming effects were found in four ERP components: the N/P150, N250, P325, and N400. Neither a change in font nor a change in size across prime and target were found to affect repetition priming in the N250, P325, and N400 components. Changing font was, however, found to affect repetition priming in the N/P150 component, while the interaction between repetition priming and size was not significant in this component. These results confirm our interpretation of the N/P150 as a component sensitive to feature-level processing, and suggest that the type of prelexical and lexical processing reflected in the N250, P325, and N400 components is performed on representations that are invariant to changes in both font and size.

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Erratum

Acknowledgements

This research was supported by grants HD25889 and HD043251.

Thanks to Irving Biederman for helpful discussion of size and shape invariance in visual object recognition, and to two anonymous reviewers for helpful comments on an earlier version of this work.

Notes

¹Here we use the term ‘shape invariance’, applied to the specific case of perceiving printed words, to refer to the ability to recognise words presented in different formats (different fonts and/or different case). Vision scientists typically use the term to refer to our ability to perceive objects from different viewpoints, with different orientations and different sizes.

²Although there is a reasonable case to be made in favour of case-specific letter representations, at least for visually dissimilar pairs of upper- and lower-case letters (e.g., a-A), it would not appear reasonable to assume the existence of font-specific letter representations. Difficulties in processing an unusual font could be achieved by a tuning process that adjusts the recognition process in order to optimise processing of atypical stimuli (e.g., Gauthier, Wong, Hayward, & Cheung, 2006; Sanocki, 1988).

³We do acknowledge that our size manipulation may not have been severe enough to observe an interaction with repetition priming in the present study. Majaj, Pelli, Kurshan, and Palomares (2002) have shown that the critical spatial frequency channel for letter identification varies with more extreme manipulations of letter size. Future research should therefore involve a parametric manipulation of size differences across prime and target stimuli with more extreme end points.