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Biomedical subjects

L E Krueger

Publications and source records attributed to L E Krueger.

8 recordsLinked to original sources
PubMed1992

The word-superiority effect and phonological recoding.

Previous work indicates that the locus of the word-superiority effect in letter detection is nonvisual and that letter names, but not letter shapes, are more accessible in words than in nonwords, that is, scrambled collections of letters (e.g., Krueger & Shapiro, 1979; Krueger & Stadtlander, 1991; Massaro, 1979). The nonvisual (verbal or lexical) coding may be phonological, or it may be more abstract. In the present study, a word advantage in the speed of letter detection was found even when the target letter was silent in the six-letter test word (e.g., s in island). Other test words varied in their frequency of occurrence in English and number of syllables (1, 2, or 3). The word advantage was larger for higher frequency words but was not affected by syllable length. The presence of unpronounceable nonwords and silent letters in the words discouraged reliance upon the phonological code but did not thereby eliminate the word advantage. Thus, the word-superiority effect with free viewing is not based entirely upon phonological recoding.

Adult↗
PubMed1991

Determination of HBsAg subtypes in different high risk populations using monoclonal antibodies.

Monoclonal antibodies with restricted specificity were used in a modified commercial enzyme immunoassay for detection of HBsAg to subtype HBsAg in sera from 122 Southeast Asian refugees entering the United States, 62 inmates of a correctional facility, and 19 homosexual men. This method was able to classify HBsAg as aywl-2, ayw3, ayw4, ayr, adw2, adw4, or adr. The HBsAg subtype was identified in 183 (90.1%) of the serum samples, but the serum HBsAg concentration was too low to determine the subtype for the 20 (9.9%) remaining samples. Among the Southeast Asian refugees, aywl-2 was demonstrated in 35 (33.0%) of the subtyped serum samples, the adw2 subtype was identified in 33 (31.1%) sera, adr was detected in 37 (34.9%) sera, and the adw 4 subtype as found in 1 (0.9%). The most common subtypes in Vietnam, Laos, and Cambodia were aywl-2, adw2, and adr, respectively. In prison inmates, the ayw3 subtype accounted for 31 (52.5%) of the subtyped serum samples, an ayw2 variant and the adw2 subtype were each found in 13 (22.0%) sera, and the aywl-2 subtype was detected in 2 (3.4%) sera. Many of these inmates admitted intravenous drug use. Among homosexual men, the adw2 subtype was identified in 16 (88.9%) of the subtyped serum samples and the ayw3 subtype was detected in 2 (11.1%) sera. This subtyping method can distinguish between most of the nine major HBsAg subtypes and can be easily performed with these monoclonal antibodies and commercially available reagents.

Antibodies, Monoclonal↗
PubMed1991

Detection of letter repetition in words and nonwords: the effect of opposite-case distractors.

This study tested whether it is the repetition of the letter's name and not its shape that is detected faster in a word than in a nonword (Krueger, 1989). Ss judged whether the same letter shape or the same letter name was repeated in a 6-letter word or nonword. When the shape was repeated, the word advantage was nearly as large (about 50 ms) when Ss looked for a physical match as when they looked for a name match. When the 2 repeated letters differed in case, however, the word advantage was very large (208 ms) when Ss looked for a name match and were thus rewarded for nonvisual coding, but the advantage vanished ((-35)-ms word deficit) when Ss looked for a physical match and were thus penalized for nonvisual coding. This indicates that letter names are much more accessible in words than in nonwords, and that words are primarily encoded nonvisually.

Adult↗
PubMed1990

Poverty and HIV seropositivity: the poor are more likely to be infected.

We analyzed demographic and behavioral risk factors for HIV seropositivity using data from 3601 clients of the main HIV counseling and testing clinic for high-risk people in Seattle, Washington, USA. Clients with lower income were found to be more likely to be HIV seropositive, before and after controlling for other demographic and risk factors with logistic regression. This result supports the hypothesis that the impoverished are at increased risk for HIV infection due to the physical and social circumstances in which their poverty places them. These may include poor access to risk-reduction information and less support for implementation of risk-reduction strategies.

Acquired Immunodeficiency Syndrome↗
PubMed1979

A model of unidimensional perceptual matching.

Faster same than different judgments typically are obtained when two letters are compared. When two tones that might differ only on frequency are compared, however, same judgments typically are slower than different judgments. A uniprocessor, unidimensional model, based on Krueger's noisy-operator theory, was fitted satisfactorily to data from four published studies of tone comparison. The model predicts faster response time on different judgments because of heterogeneity of difference. Because the second tone in a pair typically may be either higher or lower in frequency than the first, there will be a greater variety of perceived difference counts on different pairs than on same pairs. As a result, a large difference count will be decisive and will lead to an immediate "different" response, because it can be produced only by a different pair, whereas a small difference count will not be so decisive because it can be produced by either a same or a different pair. Consequently, there generally will be more rechecking on same than different pairs, and thus longer RT on same pairs.

Auditory Perception↗
PubMed1979

Features versus redundancy: comments on Massaro, Venezky, and Taylor's "Orthographic regularity, positional frequency, and visual processing of letter strings".

Massaro, Venezky, and Taylor (1979) found only a modest effect of familiarity on letter search, apparently because they pitted pseudowords (rather than real words) against nonwords and used lowercase rather than uppercase letters. Precuing the target letter seemed to reduce the familiarity effect they found yet further, but this conclusion is clouded by the fact that reaction time data were compared with accuracy data. Because similarity between target and nontarget letters tended to have more of an effect when familiarity had less of an effect. Massaro et al. proposed a successive model, with features being detected in the first stage and orthographic structure being used in a second stage. However, a concurrent model, with a self-terminating race between lower and higher level processes, can account for the data just as well. Data from Massaro et al. and from Krueger decisively demonstrate that there is a familiarity effect based on sequential redundancy over and above any effect based on spatial redundancy (Mason 1975). The Massaro et al. data also indicate that the relative familiarity effect is constant across various age groups (Krueger, Keen & Rublevich, 1974).

Cues↗