Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Effects of reappearance of fixated and attended stimuli upon saccadic reaction time (1990)
    Springer
    Experimental brain research 81 (1990), S. 318-324 
    Details
    ISSN: 1432-1106
    Keywords: Attention ; Fixation ; Saccadic reaction time Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of visual attention and fixation upon the distribution of saccadic latencies: express (E-), fast regular (FR-), and slow regular (SR-) saccades were investigated. Extinguishing a fixation or an attention point 200–300 ms before target onset increases the incidence of E-saccades while concurrently decreasing the proportion of SR-saccades. Since this extinction forces a disengaging of attention, these changes in relative proportions of saccades reflect the elimination of one of the steps involved in programming saccades. It is shown that a previously attended stimulus has a favored status relative to other stimuli in the visual field. If, after being turned off, the previously attended fixation point or a peripheral attention stimulus is turned on near the time of the target's appearance, the occurrence of the E-saccades is greatly reduced. However, the appearance of any other stimulus in the visual field at or near the time of the target onset does not inhibit E-saccades. Contrary to the conclusions reached by Posner and Cohen (1984), a stimulus presented at the formerly attended location can attract attention more efficiently than a stimulus presented at another, new location.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00228122
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Relationship between directed visual attention and saccadic reaction times (1988)
    Springer
    Experimental brain research 73 (1988), S. 546-552 
    Details
    ISSN: 1432-1106
    Keywords: Attention ; Fixation ; Saccades ; Saccadic reaction times
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Saslow (1967) and Fischer and Ramsperger (1984) found that saccadic reaction time (SRT) depends on the interval between the fixation point offset and the target onset. Using a continuously visible fixation point, we asked whether a similar function would be obtained if subjects attended to a peripherally viewed point extinguished at variable intervals before or after the target onset. The interval was varied between -500ms (i.e., attention stimulus offset after saccade target onset = overlap trials) and 500ms (i.e., attention stimulus offset before saccade target onset = gap trials). The results show a constant mean SRT of about 240 ms for overlap trials, and a U-shaped function with a minimum of 140 ms, at a gap duration of 200 ms, for gap trials. These findings suggest that saccadic latencies do not depend on the cessation of fixation per se, but rather on the disengagement of attention from any location in the visual field. The time required for subjects to disengage their attention is approximately 100 ms. This disengaged state of attention — during which short latency (express) saccades can be made — can be sustained only for a gap duration of 300 ms. At longer gap durations mean SRTs increase again.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00406613
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Analyse der Methylolmelamine durch Dünnschicht- und Gel-Chromatographie (1979)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 294 (1979), S. 375-378 
    Details
    ISSN: 1618-2650
    Keywords: Analyse von Methylolmelaminen ; Chromatographie, Dünnschicht/Chromatographie, Gel ; Melamin-Formaldehyd-Harze
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die dünnschicht-chromatographische Trennung der verschiedenen Methylolmelamine kann man durch Verwendung von DMF/H2O/ CHCl3/Isopropanol (im Volumenverhältnis 1∶1∶1∶3) als Fließmittel und Cellulose als Sorptionsmittel verbessern. Gel-chromatographisch lassen sich mit Sephadex LH 20 als stationärer Phase und DMF als Elutionsmittel die meisten Methylolmelamine als gut erkennbare Peaks trennen, so daß man anhand der Gel-Chromatogramme die Verteilung der Methylolierungsprodukte und den Verlauf der Methylolierung von Melamin verfolgen kann.
    Notes: Summary Thin-layer Chromatographic separation of the different methylolmelamines can be improved by applying DMF/H2O/CHCl3/isopropanol (1∶1∶1∶3 by volume) as eluting solvent and cellulose as layer material. Using Sephadex LH 20 as stationary phase and DMF as eluent the gel-permeation chromatographic separation of different methylolmelamines can be achieved. The distribution of the initial reaction products of melamine and formaldehyde and the course of the methylolization reaction can be observed by gelpermeation chromatograms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00468526
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...