Faster than the speed of rejection: object identification processes during visual search for multiple targets

When engaged in a visual search for two targets, participants are slower and less accurate in their responses, relative to their performance when searching for singular targets. Previous work on this “dual-target cost” has primarily focused on the breakdown of attentional guidance when looking for two items. Here, we investigated how object identification processes are affected by dual-target search. Our goal was to chart the speed at which distractors could be rejected, to assess whether dual-target search impairs object identification. To do so, we examined the capacity coefficient, which measures the speed at which decisions can be made, and provides a baseline of parallel performance against which to compare. We found that participants could search at or above this baseline, suggesting that dual-target search does not impair object identification abilities. We also found substantial differences in performance when participants were asked to search for simple versus complex images. Somewhat paradoxically, participants were able to reject complex images more rapidly than simple images. We suggest that this reflects the greater number of features that can be used to identify complex images, a finding that has important consequences for understanding object identification in visual search more generally. (PsycINFO Database Record (c) 2016 APA, all rights reserved

Using multidimensional scaling to quantify visual similarity in visual search and beyond

Visual search is one of the most widely studied topics in vision science, both as an independent topic of interest, and as a tool for studying attention and visual cognition. A wide literature exists that seeks to understand how people find things under varying conditions of difficulty and complexity, and in situations ranging from the mundane (e.g., looking for one's keys) to those with significant societal importance (e.g., baggage or medical screening). A primary determinant of the ease and probability of success during search are the similarity relationships that exist in the search environment, such as the similarity between the background and the target, or the likeness of the non-targets to one another. A sense of similarity is often intuitive, but it is seldom quantified directly. This presents a problem in that similarity relationships are imprecisely specified, limiting the capacity of the researcher to examine adequately their influence. In this article, we present a novel approach to overcoming this problem that combines multi-dimensional scaling (MDS) analyses with behavioral and eye-tracking measurements. We propose a method whereby MDS can be repurposed to successfully quantify the similarity of experimental stimuli, thereby opening up theoretical questions in visual search and attention that cannot currently be addressed. These quantifications, in conjunction with behavioral and oculomotor measures, allow for critical observations about how similarity affects performance, information selection, and information processing. We provide a demonstration and tutorial of the approach, identify documented examples of its use, discuss how complementary computer vision methods could also be adopted, and close with a discussion of potential avenues for future application of this technique

The low EOMES/TBX21 molecular phenotype in multiple sclerosis reflects CD56+ cell dysregulation and is affected by immunomodulatory therapies

Multiple Sclerosis (MS) is an autoimmune disease treated by therapies targeting peripheral blood cells. We previously identified that expression of two MS-risk genes, the transcription factors EOMES and TBX21 (ET), was low in blood from MS and stable over time. Here we replicated the low ET expression in a new MS cohort (p < 0.0007 for EOMES, p < 0.028 for TBX21) and demonstrate longitudinal stability (p < 10− 4) and high heritability (h2 = 0.48 for EOMES) for this molecular phenotype. Genes whose expression correlated with ET, especially those controlling cell migration, further defined the phenotype. CD56 + cells and other subsets expressed lower levels of Eomes or T-bet protein and/or were under-represented in MS. EOMES and TBX21 risk SNP genotypes, and serum EBNA-1 titres were not correlated with ET expression, but HLA-DRB1*1501 genotype was. ET expression was normalised to healthy control levels with natalizumab, and was highly variable for glatiramer acetate, fingolimod, interferon-beta, dimethyl fumarate

Characterising the Molecular Phenotypes of MS: heredity, gene expression modules, dysregulated immune cell subsets and response to therapy

Background: Current MS therapies target the systemic circulation. We previously identified that genes encoding transcription factors were over-represented amongst MS risk factors, and that expression of several of these were altered in MS blood, including EOMES, TBX21 and ZMIZ1. Expression was stable over time, so that it defines a molecular phenotype. Objectives: Here we tested if this finding could be replicated in independent cohorts, if expression was heritable, longitudinally stable, affected by therapy, and associated with genetic and environmental risk factors. We sought the immune cell subsets expressing these transcription factors, and tested if protein expression was also altered. Methods: Whole blood mRNA expression was determined in new cohorts of untreated MS (n = 23, Sydney; n = 47, Perth) and healthy controls (n = 23) and protein expression determined by flow cytometry in PBMCs of untreated MS and healthy controls (n = 28, 30 respectively). Effect of major therapies and correlation of gene expression with risk SNP genotypes, and anti-Epstein Barr Virus EBNA-1 titres was assessed, and heritability tested in a large twin cohort. Results: MS Molecular Phenotypes were replicated in new cohorts. Modules of genes, whose expression correlated with EOMES/TBX21 or ZMIZ1, further defined the phenotypes. CD56+ cells, inflammatory monocytes and plasmacytoid dendritic cells expressed lower levels of Molecular Phenotype transcription factors. EOMES and TBX21 risk SNP genotypes, and serum EBNA-1 titres were not correlated with gene expression, but HLA-DRB1*1501 genotype was. Therapies altered expression levels (e.g. TBX21 returned to control levels on natalizumab) with significant variability between individuals. Conclusions: EOMES/TBX21 and ZMIZ1 tag molecular phenotypes of MS that are affected by therapy. The phenotypes are due to under-representation and altered state of CD56+ and inflammatory monocytes/pDCs respectively. The dysregulated immune cells are a novel target for therapy and, together with gene expression, represent potential biomarkers of therapeutic response

Competition effects in phonological priming: the role of mismatch position between primes and targets.

International audienceIn three experiments, we examined lexical competition effects using the phonological priming paradigm in a shadowing task. Experiments 1A and 1B showed that an inhibitory priming effect occurred when the primes mismatched the targets on the last phoneme (/bagar/-/bagaj/). In contrast, a facilitatory priming effect was observed when the primes mismatched the targets on the medial phoneme (/viraj/-/vilaj/). Experiment 2 replicated these findings with primes presented visually rather than auditorily. The data thus indicate that the position of the mismatching phoneme is a critical factor in determining the competition effect between prime and target words

The autoimmune risk gene ZMIZ1 is a vitamin D responsive marker of a molecular phenotype of multiple sclerosis

Multiple Sclerosis (MS) is a neurological condition driven in part by immune cells from the peripheral circulation, the targets for current successful therapies. The autoimmune and MS risk gene ZMIZ1 is underexpressed in blood in people with MS. We show that, from three independent sets of transcriptomic data, expression of ZMIZ1 is tightly correlated with that of hundreds of other genes. Further we show expression is partially heritable (heritability 0.26), relatively stable over time, predominantly in plasmacytoid dendritic cells and non-classical monocytes, and that levels of ZMIZ1 protein expression are reduced in MS. ZMIZ1 gene expression is increased in response to calcipotriol (1,25 Vitamin D3) (p < 0.0003) and associated with Epstein Barr Virus (EBV) EBNA-1 antibody titre (p < 0.004). MS therapies fingolimod and dimethyl fumarate altered blood ZMIZ1 gene expression compared to untreated MS. The phenotype indicates susceptibility to MS, and may correspond with clinical response and represent a novel clinical target

Articulation effects in melody recognition memory

10.1080/17470218.2013.766758Quarterly Journal of Experimental Psychology6691774-179