Biomedical subjects

Thomas Jacobsen

Publications and source records attributed to Thomas Jacobsen.

25 records · Page 2Linked to original sources

PubMed2003

Timed picture naming in seven languages.

Timed picture naming was compared in seven languages that vary along dimensions known to affect lexical access. Analyses over items focused on factors that determine cross-language universals and cross-language disparities. With regard to universals, number of alternative names had large effects on reaction time within and across languages after target-name agreement was controlled, suggesting inhibitory effects from lexical competitors. For all the languages, word frequency and goodness of depiction had large effects, but objective picture complexity did not. Effects of word structure variables (length, syllable structure, compounding, and initial frication) varied markedly over languages. Strong cross-language correlations were found in naming latencies, frequency, and length. Other-language frequency effects were observed (e.g., Chinese frequencies predicting Spanish reaction times) even after within-language effects were controlled (e.g., Spanish frequencies predicting Spanish reaction times). These surprising cross-language correlations challenge widely held assumptions about the lexical locus of length and frequency effects, suggesting instead that they may (at least in part) reflect familiarity and accessibility at a conceptual level that is shared over languages.

Cross-Cultural Comparison↗

PubMed2003

Descriptive and evaluative judgment processes: behavioral and electrophysiological indices of processing symmetry and aesthetics.

Descriptive symmetry and evaluative aesthetic judgment processes were compared using identical stimuli in both judgment tasks. Electrophysiological activity was recorded while participants judged novel formal graphic patterns in a trial-by-trial cuing setting using binary responses (symmetric, not symmetric; beautiful, not beautiful). Judgment analyses of a Phase 1 test and main experiment performance resulted in individual models, as well as group models, of the participants' judgment systems. Symmetry showed a strong positive correlation with beautiful judgments and was the most important cue. Descriptive judgments were performed faster than evaluative judgments. The ERPs revealed a phasic, early frontal negativity for the not-beautiful judgments. A sustained posterior negativity was observed in the symmetric condition. All conditions showed late positive potentials (LPPs). Evaluative judgment LPPs revealed a more pronounced right lateralization. It is argued that the present aesthetic judgments engage a two-stage process consisting of early, anterior frontomedian impression formation after 300 msec and right-hemisphere evaluative categorization around 600 msec after onset of the graphic patterns.

Adult↗

PubMed2003

Bonding of resin to dentin. Interactions between materials, substrate and operators.

OBJECTIVES: The general aim of this thesis was to identify and study factors that affect bonding between resin and dentin, including operator variability. MATERIALS AND METHODS: Bonding sites were generated in vivo and in vitro and compared using SEM. The effects of experimental water- or acetone-based primers on shear bond strength to dentin were studied in vitro. Fourier transform infrared spectroscopy was used to establish any detrimental effects from water on polymerization by determining the degree of conversion of thin films of resin. The interaction between phosphoric acid and dentin was analyzed by measuring calcium leaching by use of atomic absorption spectroscopy. Bond strength of composite resin was measured to dentin with various degrees of demineralization. Gap formation adjacent to composite restorations in standardized dentin cavities was studied in vitro by confocal microscopy. RESULTS: A similar morphological appearance was found for bonding sites generated in vitro vs. in vivo. An acetone-based primer was more dependent on a moist bonding technique than was a water-based system. However, water might influence bonding by interfering with the polymerization of the resin. Calcium leaching from dentin can be predicted by use of a solubility phase diagram. No correlation could be established between calcium leaching and bond strength. Gap formation was more dependent on the operator than the choice of material. A simplified all-in-one adhesive showed less operator variability compared to more complex bonding systems. CONCLUSIONS: In vitro bond testing may well indicate the outcome of in vivo trials. The solvents used in bonding agents will influence the performance and, presumably, technique sensitivity. Water rinse time after etching might be a more important consideration than etch time. In spite of the relative importance of the results presented above, the outcome of the multi-operator trial could not be predicted.

Acetone↗

PubMed2002

Visual marking for search: behavioral and event-related potential analyses.

Visual marking is an attentional mechanism of prioritizing the selection of new static or moving objects via top-down intentional inhibition of old objects [Psychol. Rev. 104 (1997) 90-122]. The present study investigated the operation of visual marking using event-related brain potentials (ERPs). Participants searched a display for one of two target letters among randomly selected letter distractors. Two item set sizes were used in a two-stage display. Half of the items appeared for 1000 ms in the first stage followed by the remainder in the second stage. Three blocked conditions were used. In the Preview condition, targets appeared as one of a set of new items in Display 2. Items in Display 1 could thus be excluded from search by visual marking. In the Control condition, old items changed when new items appeared, and the target was equally likely to be at an old or a new position. In this condition marking is unlikely to be engaged since old locations could contain the target. In the Search condition, targets appeared either in Display 1 (80%) or Display 2 (20%), and Display 1 items did not change. The results showed condition-contingent attentional modulations in the N1/N2 range. In addition, a broadly distributed centrally-preponderant sustained negativity was obtained in the 350-750 ms time range after the onset of Display 1 for the Preview-Control comparison. This latter negativity is interpreted to reflect the processes involved in setting up and maintaining of visual marking. It demonstrated an effect of visual marking well prior to Display 2 onset, thereby ruling out an account of the preview benefit solely due to attentional capture by Display 2 item onset.

Adult↗

PubMed2002

Aesthetic judgments of novel graphic patterns: analyses of individual judgments.

Aesthetic judgments were investigated using a combined nomothetic and idiographic approach. Participants judged novel graphic patterns with respect to their own personal definitions of "beauty." Judgment analysis was employed to derive individual case models of judgment strategies as well as a group model. As predicted, symmetry had the highest correlations with aesthetic judgments of beauty. Stimulus complexity was the second-highest correlate of a positive evaluation. Thus, there was agreement at the group level. The judgment analyses, however, indicated substantial individual differences. These included use of symmetry or complexity cues that were contrary to the main group use, e.g., a few participants considered nonsymmetric patterns more beautiful. These findings suggest that exclusive consideration of the group model would have leveled the individual differences and been misleading. The group model is significant; however, the individual judgment analyses represent individual patterns of judgment in a notedly more accurate way.

Adult↗

PubMed2002

Kandinsky's questionnaire revisited: fundamental correspondence of basic colors and forms?

Kandinsky postulated a fundamental correspondence between color and form. Using a variant of his historical questionnaire, 200 (92 men, 108 women) nonartist university students were divided into two groups and asked to assign the colors yellow, red, and blue to the triangle, square, and circle in a one-to-one fashion. One group worked under a mere color-form correspondence instruction, the other under an aesthetic-correspondence one, i.e., this latter group was asked to make the most beautiful color-form assignment. Participants' assignments showed a clear, stable group preference. About half of the students assigned red to the triangle, blue to the square, and yellow to the circle, respectively. This preferred assignment stood regardless of variation in instruction. Frequently, world knowledge associations were stated in the rationale for an assignment choice. The red triangle resembled a traffic sign, a warning triangle, and the yellow circle resembled the sun. Kandinsky's assignment, however, was the least preferred one. It is argued that color-form assignments as well as the motivation to produce them are due to a multitude of factors. World knowledge, education, historical change, societal, group-specific, and individual leitmotifs are all influences.

Adolescent↗

PubMedDate not supplied

Preattentive memory-based comparison of sound intensity.

Changes in the intensity of repeated, ignored sounds elicit the mismatch negativity (MMN) brain response which reflects preattentive detection of the change. It is generally assumed that the MMN in response to intensity changes reflects a memory-based comparison mechanism rather than being due to differential states of refractoriness of intensity-specific cortical neurons. In the present study, an experimental protocol consisting of 4 oddball blocks and 1 control block was used in order to separate memory-comparison-related effects from refractoriness-related ones. This design allowed an assessment of intensity MMN using physically identical stimuli with equal probability of occurrence in separate blocks, while avoiding contamination by refractoriness. Results were consistent with an MMN in response to intensity change that reflects genuine memory-based comparison.

Acoustic Stimulation↗