■Event-related potential indices of semantic
priming using masked and unmasked words:
evidence that the N400 does not reflect a post-lexical
process
■Visual search has no memory
■Electrophysiological correlates of direct
versus indirect semantic priming in normal volunteers
■Automatic Information Procession and Social Perception:
The Influence of Trait Information Presented Outside
of Conscious Awareness on Impression Formation
■The phonological similarity effect in working memory:
An ERP study comparing auditory and visual input
modalities
■The recognition potential and the word frequency effect
at a high rate of word presentation
Event-related potential indices of semantic
priming using masked and unmasked words:
evidence that the N400 does not reflect a post-lexical
process
Diana Deacon/Sean Hewitt/ Chien-Ming Yang/Masanouri Nagata
Cognitive Brain Research Vol. 9 (2) pp. 137-146
Several authors have contended that the N400 is a reflection of a post-lexical event such as that proposed by Neely and Keefe [J.H. Neely, D.E. Keefe, Semantic context effects on visual word processing: a hybrid prospective/retrospective processing theory, in: G.H. Bower (Ed.), The Psychology of Learning and Motivation: Advances in Research and Theory, Vol. 23, Academic Press, New York, 1989, pp. 207--248.], whereby the subject compares the word on the current trial to the "context" provided by the word on the preceding trial [M. Besson, M. Kutas, The many facets of repetition: A cued-recall and event-related potential analysis of repeating words in same versus different sentence contexts, Journal of Experimental Psychology: Learning, Memory and Cognition, 19 (5) (1993), 1115-1133; C. Brown, P. Hagoort, The processing nature of the N400: Evidence from masked priming. Journal of Cognitive Neuroscience, 5(1) (1993), 34--44; P.J. Holcomb, Semantic priming and stimulus degradation: Implications for the role of the N400 in language processing, Psychophysiology 30 (1993), 47--61; M.D. Rugg, M.C. Doyle, Event-related potentials and stimulus repetition in indirect and direct tests of memory, in: H. Heinze, T. Munte, G.R. Mangun (Eds), Cognitive Electrophysiology, Birkhauser Boston, Cambridge, MA, 1994]. A study which used masked primes to directly test this possibility has been reported by Brown and Hagoort [C. Brown, P. Hagoort, The processing nature of the N400: evidence from masked priming. Journal of Cognitive Neuroscience, 5(1) (1993), 34--44]. When the primes were masked, no priming effect was observed on the N400. When behavioral data were collected in the same paradigm, from another group of subjects, the usual priming effect on RT was obtained. Considered together, the data from the two groups of subjects indicated that activation of semantic representations had occurred without conscious awareness. As no N400 priming effect was observed, it was suggested that N400 must reflect a post-lexical process. This interpretation, however, is at odds with the findings of other studies which have reported N400 priming effects under conditions where post-lexical processes would not be thought to operate[J. Anderson, P. Holcomb, Auditory and visual semantic priming using different stimulus onset asynchronies: an event-related brain potential study. Psychophysiology 32 (1995), 177--190; J. Boddy, Event-related potentials in chronometric analysis of primed word recognition with different stimulus onset asynchronies, Psychophysiology 23 (1986), 232--245; D. Deacon, T. Uhm, W. Ritter, S. Hewitt, The lifetime of automatic priming effects may exceed two seconds, Cognitive Brain Research 7 (1999), 465--472; P.J. Holcomb, Automatic and attentional process: an event-related brain potential analysis of semantic priming. Brain and Language 35 (1998) 66--85]. The present study replicated Brown and Hagoort using a repeated measures design, a shorter SOA (stimulus onset asynchrony), and a slightly different threshold setting procedure. Significant priming effects were obtained on the mean amplitude of the N400 regardless of whether the words were masked or unmasked. The findings imply that the processing subserving the N400 is not postlexical, since the N400 was manipulated without the subjects being aware of the identity of the words.
Todd S. Horowitz/Jeremy M. Wolfe
Nature
Vol.394 6 August 1998 575-577
Humans spend a lot of time searching for things, such as roadside traffic signs, soccer balls or tumors in mammograms. These tasks involve the deployment of attention from one item in the visual field to the next. Common sense suggests that rejected items should be noted in some fashion so that effort is not expended in re-examining items that have been attended to and rejected. However, common sense is wrong. Here we asked human observers to search for a letter ﾔTﾕ among letters ﾔLﾕ. This search demands visual attention and normally proceeds at a rate of 20-30 milliseconds per item. In the critical condition, we randomly relocated all letters every 111 milliseconds. This made it impossible for the subjects to keep track of the progress of the search. Nevertheless, the efficiency of the search was unchanged. Theories of visual search all assume that search relies on accumulating information about the identity of objects over time. Such theories predict that search efficiency will be drastically reduces if the scene is continually shuffled while the observer is trying to search through it. As we show that efficiency is not impaired, the standard theories must be revised.
Electrophysiological correlates of direct versus indirect semantic priming in normal volunteers
Matthias Weisbrod/Markus Kiefer/Sabine Winkler/Sabine Maier/Holger
Hill/Daniela Roesch-Ely/Manfred Spitzer
Cognitive Brain Research Vol. 8 (3) pp. 289-298
The N400 component of event related potentials (ERP) was studied in 27 right-handed healthy subjects in a speeded lexical decision task. The semantic distance between primes (always words) and targets (50% words, 50% non-words) was systematically varied. Prime--target relations included directly related words (hen--egg), indirectly related words (lemon--sweet), and non-related words (sofa--wing). ERPs were recorded from 20 scalp electrodes positioned according to the international 10--20 system. The N400 reflected semantic distance with the most negative and latest N400 peak in the non-related condition, the least negative and earliest N400 peak in the direct condition and the peak in the indirect condition in-between. Hence, N400 priming effect in the indirect condition was obtained in the absence of strong sentential constraints and even though the mediating word was physically not present.
Automatic Information Procession
and Social Perception:
The Influence of Trait Information Presented Outside of Conscious Awareness
on Impression Formation
John A. Bargh./Paula Pietromonaco
Journal of Personality and Social Psychology, 1982, 43, 3, 437-44
The accessibility of a category in memory has been shown to influence the selection and interpretation of social information. The present experiment examined the possibility that information relevant to a trait category (hostility) presented outside of conscious awareness can temporarily increase that category's accessibility. Subjects initially performed a vigilance task in which they were exposed unknowningly to single words. Either 0%,20%,or 80% of these words were semantically related to hostility. In an ostensibly unrelated second task,subjects read a behavioral description of a stimulus person that was ambiguous regarding hostility,and then rated the stimulus person on several trait ementions. The amount of processiong subjects gave to the hostile information and the negativity of their ratings of the stimulus person both were exposed. Several control conditions confirmed that the words were not consciously perceived. It was concluded that social stimuli of which people are not consciously aware can influence conscious judgements.
The phonological similarity effect
in working memory:
An ERP study comparing auditory and visual input
modalities
M. Martin-Loeches/S. R. Schweinberger/ W. Sommer
Journal of Psychophysiology 12 (1998) 144-158
The aim of this study was to assess whether the phonological similarity effect on working memory involves the same brain structures regardless of input modality, in order to test cognitive models assuming a unique and common mechanism as the locus of action of this effect. For this purpose, event-related potentials (ERPs) were recorded while serially presented letters which could be either phonologically similar or dissimilar were memorized. Letters were presented either in the auditory or visual modality. Performance results showed significant phonological similarity effects in both modalities, consisting in an increase of error rates. Additionally, the phonological similarity effect was significantly higher in the auditory than in the visual modality. ERP results in the auditory modality replicated previous findings, showing the increase of an Nd-like component associated to the phonological similarity effect. This was suggested to reflect stimulus processing at the phonological analysis level. The visual ERP effect of phonological similarity consisted of an increased temporo-occipital N1-like component, particularly over the left hemisphere. This was again interpreted as reflecting perceptual processing of verbal information, but indicating the involvement of structures specific for visual information. At variance with models that propose the phonological similarity effect to act exclusively at the phonological short-term store, our findings seem to indicate that the effect may also involve other mechanisms such as modality-specific perceptual processes.
The recognition potential and the word frequency effect at a high rate of word presentation
Alan P. Rudell
Cognitive Brain Research Vol. 8 (2) pp. 173-175
The short latency of the recognition potential (RP) suggests that it might be evoked at a high rate, which could speed noise reduction through averaging. Words were presented at 800 ms intervals. Mean RP latency for 16 subjects was 266 ms for high and 292 ms for low frequency words. The difference was statistically significant. The data suggest that word frequency affects an early stage of processing, which operates by the time the RP is evoked.