摘要:

AbstractSelective attention effects on reflexes and evoked potentials are reviewed with the aim of evaluating three theories regarding sensory automaticity. (a) Theperipheral‐gating theory, which assumes that ignored stimuli can be filtered out soon after transduction, was tentatively rejected because neither auditory‐nerve nor retinal potentials are reliably affected by attention. (b) At the other extreme, the assumption that sensory analyses are obligatory and cannot benefit from attentional resources (i.e.,strong‐automaticity theory) was also rejected, because longer latency componets were found to be modifiable by attention. (c) Anintermediate theoryprovides the best fit to present electrophysiological data. The earliest sensory analyses are assumed to be strongly automatic and then, at forebrain levels, there is a transition from strong to weak automaticity (i.e., analyses are obligatory but modifiable by attention). This transition can begin as early as about 15 ms for audition and about 80 ms for v

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1993.tb02065.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractTwo experiments studied the effects of intermodality change on electrodermal responses and on reaction time to a secondary task probe stimulus after 24 habituation training trials with either a tone or a vibrotactile stimulus. The probe was a visual stimulus of 500 ms duration, and within‐stimulus probes occurred 300 ms following stimulus onset. Experiment 1 crossed change versus no change with modality of the training stimulus. Skin conductance responses (SCRs) were larger in the experimental group than in the control on the test trial, and in the experimental group, test trial responses were larger than those on the first training trial. Probe reaction time was slower on the test trial in the experimental group than in the control, and within‐stimulus probe reaction time was slower than interstimulus interval reaction time early in the habituation series. Experiment 2 crossed change versus no change with the presence of a secondary task. Test trial SCRs were larger in the experimental group than in the control, regardless of whether or not the secondary task was present. In addition, test trial responses in the experimental group were larger than those on the first training trial in both the task and no‐task conditions. Within the task condition, reaction time was slower in the experimental condition than in the control on the test trial. In addition, reaction time in the experimental condition was slower during the change trial than during the first training stimulus. The data provide difficulties for noncomparator theories of habituation and seem to be most easily explained by theories of habituation that emphasize the importance of an extrapolatory pr

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1993.tb02066.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe mismatch negativity (MMN) component of the auditory event‐related potential (ERP) is elicited by infrequent, physically deviant stimuli in a sequence of frequent homogeneous stimuli (standards). It has been suggested that the MMN is generated by an automatic (attention‐independent) neural mismatch process with a memory trace that encodes the physical features of the standard stimulus. The proposed MMN independence of attention was addressed in the present study. Standard stimuli and two types of deviant stimuli, differing from standards either in frequency or intensity, were dichotically presented in random order and at a very rapid rate. The subject attended either to left‐or right‐ear stimuli, counting the number of a designated type of deviants in that ear. In the present conditions of very strongly focused attention, the MMN was elicited even by frequency change in the ignored input stream, and its amplitude was very similar to that of the MMN elicited by equivalent deviant stimuli (targets) in the attended input stream. In contrast, the MMN to intensity deviation was clearly attenuated in the absence of attention. This effect is, however, probably due to the attention effect on the MMN generator itself rather than the antecedent sensory‐analysis and ‐storin

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1993.tb02067.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractNineteen adolescents (average age 15 years, 3 months) were tested and retested using a standard 40 target, auditory oddball ERP paradigm across an interval of 1 year, 10 months to determine reliability of the ERP components, both in terms of intersubject stability and score agreement and in terms of trait (between‐session reliability) versus state (within‐session reliability). Significant trait stability was found for the N100, P200, and P300 latencies (r= .48, .51, and .74, respectively), and for P300 amplitude (r= .62), supporting the P300 as a reliable measure, with the stability required for group research but not necessarily for clinical applications. Discussion and examples illustrate the application of reliability information to the planning and evaluation of ERP paradi

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1993.tb02068.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe present study examined two issues. Are skin conductance responses conditioned to fear‐relevant stimuli, as contrasted with responses conditioned to fear‐irrelevant stimuli, elicited after merely an automatic, nonconscious analysis of the stimulus content? Do fearful subjects show better conditioning to nonfeared but fear‐relevant stimuli (e.g., conditioning to spiders in snake‐fearing subjects) than do nonfearful subjects? Subjects afraid of snakes, but not of spiders, or vice versa (n= 32) and nonfearful subjects (n= 32) were shown either fear‐relevant stimuli (snakes or spiders and rats) or fear‐irrelevant stimuli (flowers and mushrooms) in a differential conditioning paradigm, where one of the stimuli was followed by an electric shock. During a subsequent extinction phase, the conditioned stimuli were presented under backward masking conditions, preventing their conscious recognition. Consistent with our hypothesis, during the masked extinction of the conditioned stimuli, differential skin conductance responses to conditioning and control stimuli remained only for subjects conditioned to fear‐relevant stimuli. Both fearful and nonfearful control subjects had significantly larger differential electrodermal responses to fear‐relevant than to fear‐irrelevant stimuli. However, contrary to our hypothesis, fearful subjects did not show enhanced conditionability to their nonfeared but fear‐relevant stimuli as compared with nonfearf

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1993.tb02069.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe mediation of heartbeat perception by cardiodynamic parameters was investigated by experimentally introducing changes in heart performance. Twenty‐five subjects (14 women 11 men) underwent bicycle ergometric exercises (0–75 W) at different tilt angles (90°‐0°), After each of the 31 tilt/exercise phases, the following measures of cardiac performance were taken using impedance cardiography: stroke volume, Heather Index (as an indicator of contractile force), heart rate, and an estimate of the momentum of the ejected blood mass. Additionally, a heartbeat perception task was performed. The different tilt/exercise combinations induced profound changes in all cardiodynamic. measures, The correlation between heartbeat perception and cardiodynamic parameters was highest for “momentum”(r= 67) and for stroke volume (r= 59). From our data, we infer that intraindividually occurring changes in cardiac perception are mediated partially by characteristics of heart dynamics and that the source of these interoceptive signals lies in the heart or in its clo

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1993.tb02070.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractEffects of mild binocular anomalies on early and late evoked response complexes to word stimuli were examined in visual evoked potentials (VEPs) recorded over occipital cortex, Wernicke's area, and its right side homolog in university students with (fixation disparity group) and without (normal group) fixation disparity. Stimuli were monocularly or binocularly viewed words of a paragraph presented individually for 100 ms, one per second, and a binocular control condition without linguistic content. An early complex (P125‐N170) recorded at Oz and a late complex (N170‐late P) recorded from the t4emporoparietal placements were analyzed. The early complex as not influenced by linguistic content. Binocular stimuli generally resulted in larger early and late VEP amplitudes than did monocular stimuli except that the fixation disparity group had no binocular amplitude enhancement at Oz. Left hemisphere amplitude was greater than right for all conditions, more so for words than for nonlinguistic stimuli. For words, the left hemisphere advantage was significant only for the normal group. Relationships between basic visual processing and language processing in relation to early and late complexes are considered from several perspecti

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1993.tb02071.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractRespiratory sinus arrhythmia (RSA) is frequently employed as an intra‐ and interindividual index of cardiac parasympathetic tone, although the relationship of RSA to interindividual differences in cardiac vagal tone remains questionable. Our study examined between‐ and within‐subject relations among RSA, cardiac vagal tone, and respiratory parameters. Twenty‐nine young adults performed two sessions of tasks under no medication and single and double autonomic blockade (intravenously administered propranolol and atropine). Parasympathetic tone was determined from heart period responses to complete vagal blockade. Results indicated the following. Resting RSA does not accurately predict individual differences in cardiac vagal tone. However, RSA and heart period together do predict such individual differences reasonably well. The relationship between individual variations in RSA and vagal tone is not improved by controlling respiratory parameters. Substantial cardiac vagal activity occurs during inspiration, and intraindividual variations in respiratory measures confound the association between RSA and cardiac vag

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1993.tb02072.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe experiment examined the joint effects of semantic congruity and repetition on event‐related brain potentials (ERPs) elicited in a sentence priming task. In an initial training phase, subjects were familiarized with a list of 60 congruous and incongruous sentences. During the second phase, ERPs were recorded as subjects silently read a set of 180 unconnected sentences. One third of the sentences were presented exactly as they had been seen in training (Old sentences), one third were presented for the first time (Completely New sentences), and one third involved a re‐pairing of the frames and completions of the congruous and incongruous Old sentences (New Pair sentences). The N400 congruity effect was reduced for Old as compared with Completely New and New Pair sentence completions. These results suggest that N400 reflects processes that are sensitive to both existing semantic associations and representations of previous episodes that include the context of the eliciting stimulus. A late positive component (LPC) involving a sustained positive shift in the waveform after 600 ms was largest for incon‐grous completions and occurred somewhat earlier for Old sentences. This pattern of results is consistent with the notion that the LPC is an index of episodic retrieval and elaborative processes. The data also suggest the presence of an early onset slow positive shift that is only evident for New Pair congruous sent

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1993.tb02073.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe present study explored the impact of the stimulus presentation rate on sequential effects in event‐related potentials (ERPs) and reaction times (RTs). Random series of equiprobable tones were presented at interstimulus intervals (ISIs) of 1.3, 2.1, and 2.9s. Fast and accurate choice responses to the tones were required. Although sequential effects in RTs were stable across all ISIs, the common first‐order repetition effect in P300 amplitude was only observed at the 1.3‐s ISI and not at the slower presentation rates. This dissociation between the first‐order effects in RTs and ERPs speaks against an explanation of both effects by a common expectancy mechanism. In addition, sequential effects were observed as early as about 100 ms after stimulus onset in the lateralized readiness potential. Together with similar sequential effects in P300 latency, this finding supports a continuous flow model of information pro

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1993.tb02074.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY