Slow alpha in the EEG power spectrum as an indicator for conceptual arousal]

Based on previous findings (B?sel et al., 1990) it was assumed that in concept learning tasks generating on hypotheses on a concept which has to be developed is accompanied by increases of the Alpha 1 power (7.5-10 Hz) in the spontaneous EEG activity. In this study 16 subjects performed five problem solving tasks with similar processing requirements. EEG data were analyzed by means of post hoc comparisons of subjects differing in performance quality. Additionally, four control tasks were employed in which, based on previous studies, variations in the Theta frequency range were expected. An effect in the Alpha 1 frequency band was observed in tasks requiring reconstructive recall or testing the usefulness of an mathematical algorithm. The creation of a rank order or mental map is accompanied by power increases in the lower portions of the Alpha 1 frequency band (7.5-8.5 Hz). Moreover a high amount of controlled variance (eta2 up to 34%) was obtained for this effect. Increases in EEG Theta power, which presumably indicate subjects' component analysis, were found before the subjects recognized parts of geometric figures or before relevant features in the "buddhist monk problem" were discriminated. The dynamics of EEG power over time is in examples of frequency/time plots in a figure, illustrated.     

EMG reactions of mimetic muscles after repeated presentation of pictures with positive, negative and neutral content]

Twenty male subjects (Ss) were repeatedly confronted for five seconds to pictures with positive, negative and neutral valence. During the picture presentation facial EMG-reactions of five mimic muscles (m. frontalis lateralis, m. corrugator supercilii, m. orbicularis oculi, m. zygomaticus major on the right and left side of the face) were recorded. In addition, heart rate was measured. It could be shown that during repeated presentation of pictures with positive valence the m. orbicularis oculi and the m. zygomaticus major on both sides of the face yielded enhanced average EMG-reactions as compared to the repeated presentation of pictures with negative and neutral valence. During presentation of pictures with negative valence the m. frontalis lateralis and the m. corrugator supercilii revealed enhanced EMG-reactions as compared to the repeated presentation of pictures with positive valence. Furthermore, it could be shown that during the repeated presentation of pictures with positive valence those facial muscles which mainly react during confrontation with pictures of positive valence showed a continuous decrease of EMG-activity. Facial muscles which mainly react during the presentation of pictures with negative valence do not show a continuous decrease in EMG-activity during the course of the repeated presentation of pictures with negative valence. Additionally, the EMG-activity of the m. zygomaticus major on the right and lift side of the face do not differ with respect to the mean activity and the time course during confrontation of pictures with positive valence. The m. orbicularis oculi yielded enhanced EMG-reactions during the presentation of pictures with positive valence as compared to both m. zygomaticus major muscles. The present results are discussed with respect to psychobiological theories concerning facial expression.     

Discrimination learning of rotated faces: a Markov analysis of coding and association processes]

30 subjects participated in a discrimination experiment learning face-letter associations under four rotation conditions (45 degrees, 90 degrees, 135 degrees, 180 degrees). Under each condition two thirds of the faces were presented twice, upright and rotated away from the vertical; the remaining faces were presented once, upright or rotated. Learning is described by a joint Markov model: For faces that are presented twice it assumes a separate association and encoding process (two-stage-model), for faces that are presented once it assumes an association process (all-or-none-model). The Markov model fits the data for all four rotation conditions. The angle of rotation does not affect learning for faces that are presented once. For faces that are presented twice it influences both the association and the encoding process. For the angles employed, the effect of rotation can be approximated linearly. The results suggest that the encoding of a rotated face differs increasingly from an upright face as a function of these angles of rotation. This confirms analogous conclusions from mental rotation experiments.     

Cuing effects and associative information in recognition memory

Item recognition requires discrimination of studied words from nonstudied words. Associative recognition requires subjects to discriminate studied word groups from recombinations of words from different groups. Cued recognition requires the same old-new discrimination as item recognition, but list items are presented as cues along with the test item. The results from three experiments show (1) little or no effect of cuing for low-frequency words, but (2) positive cuing effects for high-frequency words; (3) increasing levels of overall performance with increases in study time, but (4) unchanging effects of cuing with study time; and (5) stronger positive cuing effects for two cues than for one cue. Five models (Independent Cue Model, Matrix model, MINERVA 2, SAM, and TODAM) were fit to the data of Experiment 1. Each model has trouble with at least one aspect of the results. Theoretical implications and modifications are discussed at length.     

Acoustic analysis in the differentiation of Parkinson's disease and major depression

In its early stages, Parkinson's disease (P.D.) may be difficult to distinguish from major depression (M.D.) leading to inappropriate management. Both illnesses are characterized by psychomotor retardation. The neurovegetative symptoms used to diagnose M.D. are not specific and in P.D. may be due to the physical illness itself. Currently, differentiation of the two disorders relies on subjective clinical observation. Improved diagnostic accuracy based on more objective data is needed. To this end, this study used computerized acoustic analysis to contrast speech patterns in P.D. and M.D. The sample consisted of 30 P.D. patients without depression or dementia, 30 patients with uncomplicated M.D., and 31 normal controls, each 60 years of age or over. Of the acoustic variables studied, M.D. patients had significantly reduced rates of speech compared with P.D. patients. The data suggest that this temporal measure of speech may be useful in the differentiation of P.D. and M.D.     

Musical duplex perception: perception of figurally good chords with subliminal distinguishing tones.

In a variant of duplex perception with speech, phoneme perception is maintained when distinguishing components are presented below intensities required for separate detection, forming the basis for the claim that a phonetic module takes precedence over nonspeech processing. This finding is replicated with music chords (C major and minor) created by mixing a piano fifth with a sinusoidal distinguishing tone (E or E flat). Individual threshold intensities for detecting E or E flat in the context of the fixed piano tones are established. Chord discrimination thresholds defined by distinguishing tone intensity were determined. Experiment 2 verified masked detection thresholds and subliminal chord identification for experienced musicians. Accurate chord perception was maintained at distinguishing tone intensities nearly 20 dB below the threshold for separate detection. Speech and music findings are argued to demonstrate general perceptual principles.     

Temporary suppression of visual processing in an RSVP task: an attentional blink? .

Through rapid serial visual presentation (RSVP), we asked Ss to identify a partially specified letter (target) and then to detect the presence or absence of a fully specified letter (probe). Whereas targets are accurately identified, probes are poorly detected when they are presented during a 270-ms interval beginning 180 ms after the target. Probes presented immediately after the target or later in the RSVP stream are accurately detected. This temporary reduction in probe detection was not found in conditions in which a brief blank interval followed the target or Ss were not required to identify the target. The data suggest that the presentation of stimuli after the target but before target-identification processes are complete produces interference at a letter-recognition stage. This interference may cause the temporary suppression of visual attention mechanisms observed in the present study.     

On the transmission of partial information: inferences from movement-related brain potentials.

Results are reported from a new paradigm that uses movement-related brain potentials to detect response preparation based on partial information. The paradigm uses a hybrid choice-reaction go/nogo procedure in which decisions about response hand and whether to respond are based on separate stimulus attributes. A lateral asymmetry in the movement-related brain potential was found on nogo trials without overt movement. The direction of this asymmetry depended primarily on the signaled response hand rather than on properties of the stimulus. When the asymmetry first appeared was influenced by the time required to select the signaled hand, and when it began to differ on go and nogo trials was influenced by the time to decide whether to respond. These findings indicate that both stimulus attributes were processed in parallel and that the asymmetry reflected preparation of the response hand that began before the go/nogo decision was completed.     

Morphologic agrammatism following a right hemisphere stroke in a dextral patient.

There is evidence of two major components of grammatic function in the brain: (1) morphologic, probably based in the postcentral perisylvian cortex, encompassing the selection of individual words and inflectional endings according to the rules of grammar; and (2) syntactic, probably based in the frontal lobes, encompassing construction of the overall structure of a sentence (syntax) to match the concept being considered. We present a stroke patient with impaired morphology but, unlike Broca's aphasics, relative sparing of syntax. He omitted 43% of articles, 40% of complementizers, 20% of pronouns, 27% of semantically marked prepositions, 43% of purely grammatic prepositions, and 22% of auxiliary verbs, but his average sentence length was 9.8 words and 64% of his sentences contained embedded clauses. He frequently intermingled two sentences to convey a given concept, juxtaposing words in grammatically unacceptable ways. This intermingling may represent either a grammatic "conduite d'approche," or a failure of the filtering function of a defective morphologic processor. His great difficulty in completing syntactic frames suggests that a more general form of the processes underlying grammatic morphology may play an important role in phrase structure generation.