The article analyzes the problem of top-down influences on visual information processing by the example of the phenomenon «the word superiority effect». The authors illustrate the situation of visual search of a letter in alphabetic lines, where the letter may be in a random string of letters and words. It is assumed that allocation of the word like the perceptual unit doesn’t an automatic process. The research showed that spontaneous allocation of words by search of a letter is possible; however it is mediated by the mutual arrangement of target letters and words in the form. The evidence is given that the solution of an experimental task involves not a single process of attention with phenomenal and productive aspects, but there are two classes of processes among which only one can be referred to attention.
The experimental study of top-down influences upon visual search for a target letter in large let- ter arrays has been performed. The core question of this study was whether words embedded into random letter strings — and not perceptually segregated for an observer — can influence effici- ency of the search for letters embedded either in words, or in random letter sequences between words. The experiment was based on an original modification of the classic selective attention test developed a century ago by H. Muensterberg. Participants performed visual search for a pre- defined letter of the Russian alphabet in letter matrices which included Russian words. In the first experimental condition, target letters always belonged to words, but the participants were not warned about the words, or about the arrangement of target letters in the matrix. In the second experimental condition, target letters never belonged to words. In the third (control) condition, there were no words embedded into letter matrices. The study revealed a dissociation between visual search efficiency and subjective representation of the search task. Although pre- sentation conditions did not influence search rate, the participants significantly differed in their subjective experience of this influence. If target letters belonged to words, the words subjective- ly facilitated performance; whereas, if target letters did not belong to words, the words subjecti- vely hampered the search. Moreover, if target letters were embedded in words, the participants noticed the words twice as often as in the opposite condition. We interpret this result as a disso- ciation between top-down processes in the visual system, and top-down influences upon visual search arising from chunking in visual information processing.
This volume presents new results in the study and optimization of information transmission models in telecommunication networks using different approaches, mainly based on theiries of queueing systems and queueing networks .
The paper provides a number of proposed draft operational guidelines for technology measurement and includes a number of tentative technology definitions to be used for statistical purposes, principles for identification and classification of potentially growing technology areas, suggestions on the survey strategies and indicators. These are the key components of an internationally harmonized framework for collecting and interpreting technology data that would need to be further developed through a broader consultation process. A summary of definitions of technology already available in OECD manuals and the stocktaking results are provided in the Annex section.