title: Inefficient stimulus processing at encoding affects formation of high-order general representation: A study on cross-modal word-stem completion task.
abstract: Priming is an implicit memory effect in which previous exposure to one stimulus influences the response to another stimulus. The main characteristic of priming is that it occurs without awareness. Priming takes place also when the physical attributes of previously studied and test stimuli do not match; in fact, it greatly refers to a general stimulus representation activated at encoding independently of the sensory modality engaged. Our aim was to evaluate whether, in a cross-modal word-stem completion task, negative priming scores could depend on inefficient word processing at study and therefore on an altered stimulus representation. Words were presented in the auditory modality, and word-stems to be completed in the visual modality. At study, we recorded auditory ERPs, and compared the P300 (attention/memory) and N400 (meaning processing) of individuals with positive and negative priming. Besides classical averaging-based ERPs analysis, we used an ICA-based method (ErpICASSO) to separate the potentials related to different processes contributing to ERPs. Classical analysis yielded significant difference between the two waves across the whole scalp. ErpICASSO allowed separating the novelty-related P3a and the top-down control-related P3b sub-components of P300. Specifically, in the component C3, the positive deflection identifiable as P3b, was significantly greater in the positive than in the negative priming group, while the late negative deflection corresponding to the parietal N400, was reduced in the positive priming group. In conclusion, inadequacy of specific processes at encoding, such as attention and/or meaning retrieval, could generate weak semantic representations, making words less accessible in subsequent implicit retrieval.
authors.affiliation: Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy. Electronic address: lauseba@dfb.unipi.it.
authors.forename: Laura
authors.initials: L
authors.lastname: Sebastiani
authors.affiliation: Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Castellani
authors.affiliation: Department of Surgical, Medical, Molecular & Critical Area Pathology, University of Pisa, Pisa, Italy; Institute of Clinical Physiology, National Research Council (CNR), Pisa, Italy; Extreme Centre, Scuola Superiore Sant'Anna, Pisa, Italy.
authors.forename: Angelo
authors.initials: A
authors.lastname: Gemignani
authors.affiliation: The Biorobotics Institute, Scuola Superiore Sant'Anna, Pisa, Italy.
authors.forename: Fiorenzo
authors.initials: F
authors.lastname: Artoni
authors.affiliation: Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy.
authors.forename: Danilo
authors.initials: D
authors.lastname: Menicucci
mesh_terms: D000161:Acoustic Stimulation; D001921:Brain / Q000502:physiology*; D004569:Electroencephalography; D005071:Evoked Potentials; D005260:Female; D006801:Humans; D007807:Language Tests; D008297:Male; D009483:Neuropsychological Tests; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation; D011932:Reading; D060865:Repetition Priming / Q000502:physiology*; D012660:Semantics; D012815:Signal Processing, Computer-Assisted; D013060:Speech; D013067:Speech Perception / Q000502:physiology*; D055815:Young Adult
keywords: ERPs; ErpICASSO; Priming effect; Semantic representation; Word processing