Short-term memory capacity (7 ± 2) predicted by theta to gamma cycle length ratio

The number of items that can be held in human short-term memory (STM) is limited to 7 (± 2) elements. Lisman and Idiart's theoretical model of STM proposes that this value depends on the number of gamma cycles that can fit in one theta cycle. Previous studies on animals and humans provided support for this hypothesis but direct evidence from human EEG scalp recordings has not previously been reported. We recorded spontaneous EEG activity from 17 participants and measured their verbal STM capacity with a modified digit span task from the Wechsler battery. The strong and positive correlation we found between verbal STM capacity and theta/gamma cycle length ratio thus provides a direct argument in favor of this STM theoretical model. In this study we also demonstrated a new method for assessing individual theta and gamma frequencies by detecting functional coupling between these oscillations.     

The Face of the Chameleon: The Experience of Facial Mimicry for the Mimicker and the Mimickee

This research addressed three questions concerning facial mimicry: (a) Does the relationship between mimicry and liking characterize all facial expressions, or is it limited to specific expressions? (b) Is the relationship between facial mimicry and liking symmetrical for the mimicker and the mimickee? (c) Does conscious mimicry have consequences for emotion recognition? A paradigm is introduced in which participants interact over a computer setup with a confederate whose prerecorded facial displays of emotion are synchronized with participants’ behavior to create the illusion of social interaction. In Experiment 1, the confederate did or did not mimic participants’ facial displays of various subsets of basic emotions. Mimicry promoted greater liking for the confederate regardless of which emotions were mimicked. Experiment 2 reversed these roles: participants were instructed to mimic or not to mimic the confederate’s facial displays. Mimicry did not affect liking for the confederate but it did impair emotion recognition.     

Perceptual learning can reverse subliminal priming effects

Masked primes presented prior to a target can result in inverse priming (i.e., benefits on trials in which the prime and the target are mapped onto opposite responses). In five experiments, time-of-task effects on subliminal priming of motor responses were investigated. First, we replicated Klapp and Hinkley's (2002) finding that the priming effect is initially straight (i.e., it benefits congruent trials, in which the prime and targets are mapped onto the same response) or absent, and only later reverses (i.e., faster responses in incongruent than in congruent trials). We show that the presentation of the mask plays a crucial role in this reversal and that the reversal occurs later if the mask pattern is very complex. We suggest that perceptual learning improves the recognition of task-relevant features. Once recognized, these features can trigger the preparation of the alternative response and/or inhibit the prime-activated response. These findings support an active role of the mask in priming.     

Redundant sensory information does not enhance sequence learning in the serial reaction time task

In daily life we encounter multiple sources of sensory information at any given moment. Unknown is whether such sensory redundancy in some way affects implicit learning of a sequence of events. In the current paper we explored this issue in a serial reaction time task. Our results indicate that redundant sensory information does not enhance sequence learning when all sensory information is presented at the same location (responding to the position and/or color of the stimuli; Experiment 1), even when the distinct sensory sources provide more or less similar baseline response latencies (responding to the shape and/or color of the stimuli; Experiment 2). These findings support the claim that sequence learning does not (necessarily) benefit from sensory redundancy. Moreover, transfer was observed between various sets of stimuli, indicating that learning was predominantly response-based.     

A Constructive Type-Theoretical Formalism for the Interpretation of Subatomically Sensitive Natural Language Constructions

The analysis of atomic sentences and their subatomic components poses a special problem for proof-theoretic approaches to natural language semantics, as it is far from clear how their semantics could be explained by means of proofs rather than denotations. The paper develops a proof-theoretic semantics for a fragment of English within a type-theoretical formalism that combines subatomic systems for natural deduction [20] with constructive (or Martin-L?f) type theory [8, 9] by stating rules for the formation, introduction, elimination and equality of atomic propositions understood as types (or sets) of subatomic proof-objects. The formalism is extended with dependent types to admit an interpretation of non-atomic sentences. The paper concludes with applications to natural language including internally nested proper names, anaphoric pronouns, simple identity sentences, and intensional transitive verbs.     

Socratic Proofs for Quantifiers

First-order logic is formalized by means of tools taken from the logic of questions. A calculus of questions which is a counterpart of the Pure Calculus of Quantifiers is presented. A direct proof of completeness of the calculus is given. *Research for this paper was supported by The Foundation for Polish Science (both authors), and indirectly (in the case of the first author) by a bilateral exchange project funded by the Ministry of the Flemish Community (project BIL 01/80) and the State Committee for Scientific Research, Poland.     

Language Switching in the Production of Phrases

The language switching task has provided a useful insight into how bilinguals produce language. So far, however, the studies using this method have been limited to lexical access. The present study provides empirical evidence on language switching in the production of simple grammar structures. In the reported experiment, Polish–English unbalanced bilinguals switched between their L1 and L2 while describing pictures of ongoing and completed actions with simple SV progressive and perfective phrases. The results show asymmetrical switching costs for progressive phrases and symmetrical switching costs with reversed dominance for perfective phrases. These findings parallel those obtained in tasks requiring the production of single words, although the present study is the first in which the same bilingual participants display different patterns of switching costs depending on the characteristics of utterances they produce. These results can be explained using recently developed models of bilingual language control.     

Do Nonnative Language Speakers Chew the Fat and Spill the Beans with Different Brain Hemispheres? Investigating Idiom Decomposability with the Divided Visual Field Paradigm

The purpose of this study was to explore possible cerebral asymmetries in the processing of decomposable and nondecomposable idioms by fluent nonnative speakers of English. In the study, native language (Polish) and foreign language (English) decomposable and nondecomposable idioms were embedded in ambiguous (neutral) and unambiguous (biasing figurative meaning) context and presented centrally, followed by laterally presented target words related to the figurative meaning of the idiom or literal meaning of the last word of the idiom. The target appeared either immediately at sentence offset (Experiment 1), or 400 ms (Experiment 2) after sentence offset. Results are inconsistent with the Idiom Decomposition Hypothesis (Gibbs et al. in Mem Cogn 17:58–68, 1989a; J Mem Lang 28:576–593, 1989b) and only partially consistent with the idea of the differential cerebral involvement in processing (non)decomposable idioms [the Fine/Coarse Coding Theory, Beeman (Right hemisphere language comprehension: perspectives from cognitive neuroscience, Lawrence Erlbaum Associates, Mahwah, NJ, 1998)]. A number of factors, rather than compositionality per se, emerge as crucial in determining idiom processing, such as language status (native vs. nonnative), salience, or context.