The proximity structure of achromatic surface colors and the impossibility of asymmetric lightness matching

In asymmetric lightness matching tasks, observers sometimes report that they cannot achieve satisfactory matches between achromatic surfaces under different neutral illuminants. The surfaces appear different, yet no further adjustment of either surface improves the match. There are evident difficulties in interpreting data from a task that the observer cannot always do, and these difficulties likely affect the interpretation of a large number of previous studies. We investigated, as an alternative to asymmetric matching, the direct use of proximity judgments in the study of surface lightness perception. We asked observers to rate the perceived dissimilarity of pairs of achromatic surfaces that were placed in identical scenes and viewed under different neutral illuminants. We develop a parametric model that accurately predicts perceived dissimilarity in terms of physical light intensities and surface albedos. The parameters of this model are readily interpretable. In particular, the ratio of the influence of changes in illuminant intensity and changes in surface albedo is a measure of the extent to which the observer discounts the illuminant. Asymmetric lightness matching can be interpreted as an unachievable limiting case of proximity judgment.     

Enhanced cholinergic suppression of previously strengthened synapses enables the formation of self-organized representations in olfactory cortex

Computational modeling assists in analyzing the specific functional role of the cellular effects of acetylcholine within cortical structures. In particular, acetylcholine may regulate the dynamics of encoding and retrieval of information by regulating the magnitude of synaptic transmission at excitatory recurrent connections. Many abstract models of associative memory function ignore the influence of changes in synaptic strength during the storage process and apply the effect of these changes only during a so-called recall-phase. Efforts to ensure stable activity with more realistic, continuous updating of the synaptic strength during the storage process have shown that the memory capacity of a realistic cortical network can be greatly enhanced if cholinergic modulation blocks transmission at synaptic connections of the association fibers during the learning process. We here present experimental data from an olfactory cortex brain slice preparation showing that previously potentiated fibers show significantly greater suppression (presynaptic inhibition) by the cholinergic agonist carbachol than unpotentiated fibers. We conclude that low suppression of non-potentiated fibers during the learning process ensures the formation of self-organized representations in the neural network while the higher suppression of previously potentiated fibers minimizes interference between overlapping patterns. We show in a computational model of olfactory cortex, that, together, these two phenomena reduce the overlap between patterns that are stored within the same neural network structure. These results further demonstrate the contribution of acetylcholine to mechanisms of cortical plasticity. The results are consistent with the extensive evidence supporting a role for acetylcholine in encoding of new memories and enhancement of response to salient sensory stimuli.     

Preference ratings of images representing archetypal themes: an empirical study of the concept of archetypes

Archetype Theory is consistent with the full range of empirical psychological research, yet has not itself been empirically studied. As part of a project to integrate psychological theory, especially psychotherapeutic theory, with empirical research, I asked 151 subjects to rate their preferences for images representing archetypal themes and factor analysed their responses. The results are consistent with the hypothesis that archetypal themes determine affective responses in adults. Archetype theory may prove itself to be useful in operationalizing a number of contemporary psychological theories.     

Decision making, movement planning and statistical decision theory

We discuss behavioral studies directed at understanding how probability information is represented in motor and economic tasks. By formulating the behavioral tasks in the language of statistical decision theory, we can compare performance in equivalent tasks in different domains. Subjects in traditional economic decision-making tasks often misrepresent the probability of rare events and typically fail to maximize expected gain. By contrast, subjects in mathematically equivalent movement tasks often choose movement strategies that come close to maximizing expected gain. We discuss the implications of these different outcomes, noting the evident differences between the source of uncertainty and how information about uncertainty is acquired in motor and economic tasks.     

Evaluation of the Informational Content,Readability and Comprehensibility of Online Health Information on Monogenic Diabetes

The purpose of this study was to assess the informational content, readability, suitability and comprehensibility of websites offering educational information about monogenic diabetes available to patients. The top 20 results from 15 queries in four search engines were screened. Content analysis was performed by two independent coders. Readability was determined using Flesch-Kincaid grade level (FKGL) and Simplified Measure of Goobledygook (SMOG). The Comprehensibility Assessment of Materials (SAM + CAM) scale was utilized to evaluate website suitability and comprehensibility. Only 2% (N = 29) of 1200 screened websites met inclusion criteria. Content analysis showed that 16 websites presented information on at least the most common forms of MODY (1, 2 and 3), four addressed the utility of genetic counseling, and none included support resources for patients. All websites exceeded the consensus readability level (6th grade) as assessed by FKGL (10.1 grade) and SMOG (12.8 ± 1.5 grades). Although the majority (N = 20) of websites had an overall “adequate” to “superior” quality score (SAM + CAM score > = 40%), more than one-third scored “not suitable” in categories of content, literacy demand, graphics, and learning motivation. The online educational resources for monogenic diabetes have a high readability level and require improvement in ease of use and comprehensibility for patients with diabetes.