This paper describes an experiment to quantify texture using an artificial finger equipped with a microphone to detect frictional sound. Using a microphone to record tribological data is a biologically inspired approach that emulates the Pacinian corpuscle. Artificial surfaces were created to constrain the subsequent analysis to specific textures. Recordings of the artificial surfaces were made to create a library of frictional sounds for data analysis. These recordings were mapped to the frequency domain using fast Fourier transforms for direct comparison, manipulation and quantifiable analysis. Numerical features such as modal frequency and average value were calculated to analyze the data and compared with attributes generated from principal component analysis (PCA). It was found that numerical features work well for highly constrained data but cannot classify multiple textural elements. PCA groups textures according to a natural similarity. Classification of the recordings using k nearest neighbors shows a high accuracy for PCA data. Clustering of the PCA data shows that similar discs are grouped together with few classification errors. In contrast, clustering of numerical features produces erroneous classification by splitting discs between clusters. The temperature of the finger is shown to have a direct relation to some of the features and subsequent data in PCA.
Temporal form (continuous vs. pulsating) and shock source (alternating current vs. direct current) were factorially combined to produce four shock treatments. The effects of inescapable presentations of these stimuli on subsequent avoidance response acquisition were measured in dogs (Experiment 1) and in rats (Experiment 2) and revealed an interaction of shock variables. Initially, all groups that received ac shock showed impaired performance for the pulsating and continuous shock conditions; groups that received de continuous shock were also impaired, while those that received de pulsating shock were not. While this pattern of interference persisted for dogs, it was transient in rats, with only the ac continuous-shock group continuing to be impaired. Mean avoidance performance were positively related to mean activity levels during inescapable shocks for the de shock groups but not for the ac shock groups.
Subjects identified a single lowercase letter in a visual display by pressing one of two buttons. Two letters were assigned to each response. Groups received one of three context conditions: word, nonword, or single-letter displays. In words and nonwords, the flanking letters adjacent to the target varied as to whether they were response compatible or incompatible with the target. Single letters produced faster response latencies than either multiletter condition, and words yielded slower latencies than did nonwords. Items containing an incompatible-response flanking letter produced longer latencies than items containing a compatible flanking letter. Subgroups of subjects with different characteristic processing patterns were identified with a separate test. These subgroups were differentially affected by the context conditions in the letter-identification task. A greater subgroup difference was found in nonwords than in words.Whether or not word context directly influences the perception of letters is a question that has received considerable attention in the psychological literature for nearly a century, beginning with the work of Cattell (1886). Much of the early work suggested that letters were identified more rapidly and with greater accuracy when they appeared in words than when they appeared in nonwords or in singleletter displays (e.g., Miller, Bruner, & Postman, 1954;Postman, Bruner, & Walk, 1951;Reicher, 1969).This so-called "word superiority" effect was later analyzed as the ability to utilize the redundancy of letter sequences or orthographic regularity of the language (Aderman & Smith, 1971;Miller et al., 1954;Smith, 1969). Consistent with this notion were the findings that letters could be identified equally well in pronounceable, orthographically regular nonwords and real words (Baron & Thurston, 1973) and that letters in highly redundant nonwords were more accurately identified than letters in low redundant words (Smith, 1969).In addition to orthographic regularity, pronounceability of the context stimulus also influences performance (Gibson, Osser, & Pick, 1963;Gibson, Pick, Osser, & Hammond, 1962), as does positional frequency of the letters in the display (Mason, 1975).This research was supported, in part, by a grant to David LaBerge from the National Science Foundation (BNS-79(4677) and, in part, by grants to the Center for Research in Human Learning, University of Minnesota, from the National Institute of Child Health and Human Development (HD-01136) and from the National Science Foundation (BNS-77-22075). Reprint requests should be sent to Janice A. Lawry, Department of Psychology, University of California, Los Angeles, 405 Hilgard Drive, Los Angeles, California 90024. Estes (1975aEstes ( , 1975b has concluded that such factors as these affect response decisions rather than perceptual processes per se. When insufficient stimulus information about the target stimulus exists, subjects may utilize information from the surrounding letters to reduce the number of probable response alternatives. ...
The dependence of visual word recognition on letter processing was investigated by measuring the effect of a cue word on subsequent target word processing for various degrees of cue/ target similarity. Using a simultaneous matching task (Experiments 1 and 2), modest facilitation was found for identical cue/target items only, whereas items that differed by a single letter led to substantial interference. Targets that shared internal or external letters with cues yielded latencies comparable to those for neutral or different cue conditions. The identical facilitation and high-similarity interference was also found in a lexical decision task under normal display conditions (Experiment 3). However, when direct letter processing was measured using spatially transformed targets (Experiment 4), large facilitatory effects were found for similar as well as for identical cue/target conditions. Although both letter and word codes appear to be activated by normally displayed words, such word code activity may not routinely depend upon letter code outputs.Many models of word perception (Estes, 1977;LaBerge& Samuels, 1974; Massaro, 1975;McClelland, 1979) propose that word codes are activated by means of constituent letter codes. For these models, the link from letter to word codes is generally assumed to be direct or indirect by means of intermediate spellingpattern codes. The flow of activation may proceed in discrete steps, with letter codes reaching full activation before transmitting their output to the word code level. Alternatively, McClelland (1979) has proposed that the flow of activation from one level to the next is continuous and does not depend upon prior recognition events at lower levels. Consistent with this "cascade" assumption, sufficient activation may converge on the word code from letter or spelling pattern sources, enabling it to reach recognition criterion before any given letter or spelling pattern code reaches its particular recognition threshold.In all of these variations of the letter-to-word hierarchy model, the picture of word code activation is one of a bottom-up, stimulus-driven process in which letter codes at lower levels of the perceptual system continue to feed their outputs into higher levels of codes until a word code reaches its recognition threshold. The purpose of the present experiments is to measure this dependence of word code activation on prior letter code activation.According to the letter-to-word processing viewpoint, any display that activates a word code must necessarily have activated the constituent letter codes as well, whether or not such activation is sufficient to exceed the recognition thresholds of the letter codes. It seems reasonable, therefore, to expect that words that share letters should facilitate each other via the shared letter code participation in their recognition. For example, if a person were to see the word store just prior to the word stone, then the word stone should be processed faster than if the word laugh had preceded stone. Specifically, if stone is...
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