Empirical research in on-line trust: a review and critical assessment

Lack of trust is one of the most frequently cited reasons for consumers not purchasing from Internet vendors. During the last four years a number of empirical studies have investigated the role of trust in the specific context of e-commerce, focusing on different aspects of this multi-dimensional construct. However, empirical research in this area is beset by conflicting conceptualizations of the trust construct, inadequate understanding of the relationships between trust, its antecedents and consequents, and the frequent use of trust scales that are neither theoretically derived nor rigorously validated. The major objective of this paper is to provide an integrative review of the empirical literature on trust in e-commerce in order to allow cumulative analysis of results. The interpretation and comparison of different empirical studies on on-line trust first requires conceptual clarification. A set of trust constructs is proposed that reflects both institutional phenomena (system trust) and personal and interpersonal forms of trust (dispositional trust, trusting beliefs, trusting intentions and trust-related behaviours), thus facilitating a multi-level and multi-dimensional analysis of research problems related to trust in e-commerce.     

Unitary events in multiple single-neuron spiking activity: I. Detection and significance.

It has been proposed that cortical neurons organize dynamically into functional groups (cell assemblies) by the temporal structure of their joint spiking activity. Here, we describe a novel method to detect conspicuous patterns of coincident joint spike activity among simultaneously recorded single neurons. The statistical significance of these unitary events of coincident joint spike activity is evaluated by the joint-surprise. The method is tested and calibrated on the basis of simulated, stationary spike trains of independently firing neurons, into which coincident joint spike events were inserted under controlled conditions. The sensitivity and specificity of the method are investigated for their dependence on physiological parameters (firing rate, coincidence precision, coincidence pattern complexity) and temporal resolution of the analysis. In the companion article in this issue, we describe an extension of the method, designed to deal with nonstationary firing rates.     

Bowker's test for symmetry and modifications within the algebraic framework

Categorical data occur in a wide range of statistical applications. If the data are observed in matched pairs, it is often of interest to examine the differences between the responses. The focus is on tests of axial symmetry in two-way tables. A commonly used procedure is the Bowker test which is a generalization of the McNemar test. The test decision is based on a chi-squared approximation which might not be adequate, for example if the table is sparse. Therefore, modifications of the test statistic have been discussed. A test of symmetry based on Bowker's test and Markov Chain Monte Carlo methods is proposed. A simulation study is carried out to determine and compare the performances of the simulation test, the Bowker test and two modifications.     

On what we cannot learn from proximity data.

Different issues raised in the commentaries are elaborated in this reply. The focus was on the following five topics: (a) the nature of storage deficits in the patient groups and the different meanings that can be attached to it, (b) the possible explanations for the disordered responses of the patients, (c) suggestions for the use of other techniques to study semantic deficits, (d) the Warrington and Shallice criteria to distinguish between access and storage problems, and (e) some technical (statistical) issues raised in the commentaries. The reply concludes by highlighting the key findings reported in the target article that seem to be accepted by the large majority of the commentators. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Selective ablation of GABA neurons in the ventral tegmental area increases spontaneous locomotor activity.

γ-aminobutyric acid (GABA) neurons in the ventral tegmental area (VTA) provide innervation to cortical and subcortical regions of the brain. To solidify the importance of these VTA GABA neurons in behavioral function, we employed the neurotoxin dermorphin-saporin (DS) to selectively lesion VTA GABA neurons prior to assessing spontaneous motor activity. Rats were bilaterally microinfused with DS (1.0 or 2.0 pmol/200 nl/side) or blank-saporin control (BS, 200 nl/side) into the VTA. Seven days later, DS-treated rats exhibited significantly elevated motility in comparison with BS-treated rats; this elevated motility normalized by Day 14 following pretreatment with 1.0 pmol of DS but was sustained on Day 14 after pretreatment with 2.0 pmol of DS. A selective loss of VTA GABA neurons on Day 14 was demonstrated through reduced expression of mRNA for glutamic acid decarboxylase-67 and μ-opioid receptor, but not tyrosine hydroxylase (a dopamine neuron marker), in the VTA. Thus, a dose- and time-related selective loss of VTA GABA neurons was accomplished using this novel neurotoxin. This loss of GABA VTA neurons was associated with hypermotility, further supporting their important regulatory role in the generation of behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Bestimmung natürlich vorkommender steroidaler Sexualhormone (Androgene und Gestagene) in Rindfleisch

The content of 10 naturally occurring steroidal sex hormones (androgens and progestogens), their biosynthetic precursors and metabolites was determined in 62 samples of beef (bulls, steers, heifers). After enzymatic hydrolysis of their conjugates, the steroids were extracted from the tissue by liquid-liquid extraction and purified by solid phase extraction. The identification and quantification was carried out by GC-MS of the trimethylsilyl ethers. The progestogens progesterone and pregnenolone were quantitatively dominant (43,7 and 6,5 μg/kg respectively). The highest steroid concentrations were determined in female cattle.     

Maternal presence and rearing condition affect responses to live predator in kangaroo rats (Dipodomys heermanni arenae).

Experiment 1 compared the responses of wild-caught adult and captive-born adult and juvenile kangaroo rats (Dipodomys heermanni arenae) to a live snake. Wild-caught adult rats were less active and monitored the snake more than during a control condition; captive-born juvenile rats did not behave differently during snake and control tests. Snake-naive adult rats behaved more like the wild-caught adult rats, but not on all measures. In Experiment 2, pups were tested at 25 and 50 days of age in 4 conditions: no-snake control, alone with the snake, with a sibling and the snake, and with the mother and the snake. Pups did not behave differently during control and snake tests, but during tests with the mother, pups faced the snake less and followed the mother. Younger pups were more often near the mother than a sibling and followed the mother more when the snake was present. Development of defensive behavior may depend on both predator experience and maternal influence. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hypothesis formation as a facilitator of conceptual development.

Examined the role of hypothesis formation in the development of conceptual understanding of certain geometric principles of block design. 33 4–4? yr old children were instructed in the building of a series of 3-dimensional block designs under conditions which either permitted the use of copying strategies or mitigated against these and demanded hypothesis formation based upon partial information. No differences in error rate were found between conditions during duplication of familiar 3-dimensional block designs on a training test. Differences emerged when Ss were required to reconstruct, in 1 trial, from a photograph, familiar designs previously successfully duplicated from 3-dimensional models. Ss who originally had attempted to reconstruct 3-dimensional models under conditions requiring hypothesis formation, more accurately duplicated the complex, pictorial designs than did Ss who had reconstructed the 3-dimensional models under optimal cue conditions. Hypothesis formation, it is concluded, led to greater conceptual understanding of the geometric principles underlying the block designs. (French summary) (9 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)