Publications by authors named "Brett Cochrane"

13 Publications

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Looking into the mind's eye: Directed and evaluated imagery vividness modulates imagery-perception congruency effects.

Psychon Bull Rev 2021 Jan 14. Epub 2021 Jan 14.

Department of Psychology, Neuroscience & Behaviour, McMaster University, Hamilton, Ontario, Canada.

While most people have had the experience of seeing a representation in the mind's eye, it is an open question whether we have control over the vividness of these representations. The present study explored this issue by using an imagery-perception interface whereby color imagery was used to prime congruent color targets in visual search. In Experiments 1a and 1b, participants were required to report the vividness of an imagined representation after generating it, and in Experiment 2, participants were directed to create an imagined representation with particular vividness prior to generating it. The analyses revealed that the magnitude of the imagery congruency effect increased with both reported and directed vividness. The findings here strongly support the notion that participants have metacognitive awareness of the mind's eye and willful control over the vividness of its representations.
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http://dx.doi.org/10.3758/s13423-020-01868-8DOI Listing
January 2021

Visual imagery influences attentional guidance during visual search: Behavioral and electrophysiological evidence.

Atten Percept Psychophys 2021 Jan 30;83(1):58-66. Epub 2020 Nov 30.

Department of Psychology, Neuroscience and Behaviour, McMaster University, Hamilton, Ontario, Canada.

Recent behavioral studies have shown that color imagery can benefit visual search when it is congruent with an upcoming target. In the present study we investigated whether this color imagery benefit was due to the processes underlying attentional guidance, as indicated by the electrophysiological marker known as the N2pc component. Participants were instructed to imagine a color prior to each trial of a singleton search task. On some trials, the imagined color was congruent with the target, and on other trials, it was congruent with the distractors. The analyses revealed that the N2pc was present when color imagery was congruent with the search target, and absent when it was congruent with the distractors. Further, there was preliminary evidence that attentional guidance depended on the vividness of color imagery and the frequency at which participants implemented the imagery instruction. Overall, the results of the present study indicate that color imagery can influence the attentional guidance processes underlying visual search.
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http://dx.doi.org/10.3758/s13414-020-02208-7DOI Listing
January 2021

Context isn't everything: Search performance is influenced by the nature of the task but not the background.

Atten Percept Psychophys 2021 Jan 23;83(1):27-37. Epub 2020 Nov 23.

Department of Psychology, University of Toronto, Sidney Smith Hall, 100 St. George Street, Toronto, Ontario, M5S 3G3, Canada.

AbstractIt has been demonstrated in the literature that cues in the environment that are predictive of how a task ought to be performed can influence performance. In an extension of this general notion, Cosman and Vecera (Journal of Experimental Psychology: Human Perception and Performance, 39(3), 836-848, 2013) reported that simply performing singleton and feature search tasks when irrelevant scenes were displayed in the background automatically modulated the search strategies adopted by participants when these scenes were reinstated at a later time. While intriguing, this result was also somewhat surprising given that an adaptive system (like the human brain) should disregard irrelevant information so task competencies generalize across environments. To investigate this issue further, we replicated the experimental procedures of Cosman and Vecera, while varying whether the test phase was either a singleton search (Experiments 1 and 3) or a feature search (Experiment 2) task. While it was observed that the nature of the search task varied whether a color singleton distractor influenced performance, there was no evidence that background scenes modulated the search strategies adopted by participants, contrasting the results of Cosman and Vecera. Overall, the findings here support the conclusion that the visual system prioritizes task-relevant information while disregarding irrelevant background information.
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http://dx.doi.org/10.3758/s13414-020-02204-xDOI Listing
January 2021

Re-examining Maljkovic and Nakayama (1994): Conscious expectancy does affect the Priming of Pop-out effect.

Atten Percept Psychophys 2020 Jul;82(5):2693-2702

Department of Psychology, University of Toronto, Sidney Smith Hall, 100 St. George Street, Toronto, Ontario, M5S 3G3, Canada.

Maljkovic and Nakayama (Memory & Cognition, 22(6), 657-672, 1994) observed that color singleton search performance was faster when the target and distractor colors repeated rather than switched across trials - an effect termed Priming of Pop-out (PoP). Two of the key results of this seminal study revealed that the PoP effect was not influenced by the knowledge of the probability of a target color change (Experiment 2), nor was it influenced by anticipating the upcoming target color by subvocalizing it (Experiment 4). Based on these findings they concluded that the PoP effect reflected the automatic priming due to the persistence of the target and distractor colors of the previous trial. Based on recent findings indicating that conscious expectancy may influence the PoP effect, as well as several bygone experimental practices in the original study (i.e., experimenter participants, no inferential statistics, etc.), we felt it worthwhile to evaluate whether their findings were observed when replicated in an empirically rigorous manner. Though the present study revealed that the PoP effect was robust, it was profoundly impacted by the knowledge of the probability of a target color switch (Experiment 1) and vocally anticipating the upcoming target color (Experiment 2). Overall, the results suggest that we should abandon the notion that the PoP effect only reflects the automatic priming of the previous target and distractor colors independent of conscious expectancy.
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http://dx.doi.org/10.3758/s13414-020-02034-xDOI Listing
July 2020

The representational basis of positive and negative repetition effects.

J Exp Psychol Hum Percept Perform 2020 Mar 7;46(3):252-263. Epub 2019 Nov 7.

Department of Psychology, Neuroscience and Behaviour.

Repetition of target features in the same spatial location can either benefit or impair performance in perceptual tasks. Moreover, which of these two effects occurs can depend on whether an intervening event is presented temporally between consecutive targets. Here, we explored these effects for color feature repetitions by varying the representational overlap of consecutive targets. The second target on all experimental trials was a simple perceptual color. The task and first target were manipulated to vary the representation produced in response to the first target (perceptual representation of color in Experiment 1; imagined representation of color in Experiments 2 and 5; conceptual representation of color in Experiment 3; color-unrelated representation in Experiment 4). Perceptual and imagined color representations for the first target produced a positive repetition effect when an intervening event did not appear between targets but produced a negative repetition effect when an intervening event did appear between targets. In contrast, conceptual color and color-unrelated representations produced a negative repetition effect both with and without an intervening event. These results suggest that positive repetition effects depend on consecutive targets that share visual representations, whereas negative repetition effects reflect a more complex relationship between stimulus and response features across targets. (PsycINFO Database Record (c) 2020 APA, all rights reserved).
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http://dx.doi.org/10.1037/xhp0000713DOI Listing
March 2020

Imagined event files: An interplay between imagined and perceived objects.

Psychon Bull Rev 2019 Apr;26(2):538-544

Department of Psychology, Neuroscience and Behaviour, McMaster University, 1280 Main St. W, Hamilton, Ontario, L8S 4L8, Canada.

An important function of attention is to integrate features processed in distinct brain areas into a single coherent object representation. The immediate outcome of this binding process has been termed an event file, a transient memory structure that links features, context, and associated actions. A key result that supports the existence of event files is the partial repetition cost - slowed responses to a current event thought to reflect the updating of event file bindings in simple trial-to-trial repetition methods. In four experiments, using a procedure similar to Hommel (Visual Cognition, 5 (1/2), 183-216, 1998), we explored whether similar event file binding effects occurred when participants imagine rather than perceive a first event prior to responding to a following visual event. The results indicate that this effect does occur, implying that feature binding in imagery and perception may follow similar principles.
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http://dx.doi.org/10.3758/s13423-019-01572-2DOI Listing
April 2019

Cueing color imagery: A critical analysis of imagery-perception congruency effects.

J Exp Psychol Learn Mem Cogn 2019 Aug 26;45(8):1410-1421. Epub 2018 Jul 26.

Faculty of Health Sciences, McMaster University.

The relation between mental imagery and visual perception is a long debated topic in experimental psychology. In a recent study, Wantz, Borst, Mast, and Lobmaier (2015) demonstrated that color imagery could benefit color perception in a task that involved generating imagery in response to a cue prior to a forced-choice color discrimination task. Here, we scrutinized whether the method of Wantz et al. warrants strong inferences about the role of color imagery in color perception. In Experiments 1-3, we demonstrate that the imagery effect reported by Wantz et al. does replicate nicely using their method but does not occur when cue-target contingencies and a redundancy between the imagery and response dimensions are removed from their method. In Experiments 4-6, we explored cued imagery effects further using a method in which the cued imagery dimension was orthogonal to the response dimension. The results of these experiments demonstrate that a compelling endogenously cued imagery effect does not occur for lone targets but does occur for singleton color targets embedded amid homogenous color distractors. (PsycINFO Database Record (c) 2019 APA, all rights reserved).
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http://dx.doi.org/10.1037/xlm0000653DOI Listing
August 2019

Strategic visual imagery and automatic priming effects in pop-out visual search.

Conscious Cogn 2018 10 21;65:59-70. Epub 2018 Jul 21.

Department of Psychology, Neuroscience & Behavior, McMaster University, Hamilton, Ontario, Canada.

Priming of Pop-out (PoP) is defined by faster responses in singleton search when the target repeats across trials than when it switches. In a recent study, it was shown that the PoP effect can be reversed using visual imagery (Cochrane, Nwabuike, Thomson, & Milliken, 2018). The goal of the current study was to pinpoint the procedural constraints necessary to observe the imagery-induced reversal of PoP. Across four experiments the reversal of the PoP effect (i) depended critically on the response-stimulus interval between trials, (ii) was remarkably stable across long experimental sessions, (iii) was observed within trial-pairs when participants engaged in visual imagery, but not between trial-pairs when participants did not, and (iv) appeared to be more robust with self-paced trial-pairs than with a long continuous run of trials. Together, these results offer strong confirmation of the idea that self-generated visual imagery can produce robust reversals of the PoP effect.
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http://dx.doi.org/10.1016/j.concog.2018.07.008DOI Listing
October 2018

An imagery-induced reversal of intertrial priming in visual search.

J Exp Psychol Learn Mem Cogn 2018 Apr 2;44(4):572-587. Epub 2017 Nov 2.

Department of Psychology, Neuroscience, and Behaviour.

Maljkovic and Nakayama (1994) found that pop-out search performance is more efficient when a singleton target feature repeats rather than switches from 1 trial to the next-an effect known as priming of pop-out (PoP). They also reported findings indicating that the PoP effect is strongly automatic, as it was unaffected by knowledge of the upcoming target color. In the present study, we examined the impact of visual imagery on the PoP effect. Participants were instructed to imagine a target color that was opposite that of the preceding trial (e.g., if the prior target was red, then imagine green). Under these conditions, responses were faster for targets that matched the imagined color than for targets that matched the previous target color, reversing the typical PoP effect. There was no such reversal of the PoP effect for participants asked to verbalize rather than imagine an upcoming target color. In Experiment 3, we explored whether the PoP effect was indeed eliminated in the prior experiments, or instead obscured by the opposing visual imagery effect. Two conditions were compared, 1 in which a PoP effect could oppose the visual imagery effect, and another in which no such effect was possible, allowing inferences about whether a PoP effect was present. The results indicated that the PoP effect was present, but obscured by the larger visual imagery strategy effect that pushed performance in the opposite direction. Overall, the results suggest that the PoP effect is sensitive to top-down strategies that involve visual representations. (PsycINFO Database Record
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http://dx.doi.org/10.1037/xlm0000470DOI Listing
April 2018

Fetal Bovine Serum (FBS): Past - Present - Future.

ALTEX 2018 9;35(1):99-118. Epub 2017 Aug 9.

Division of Physiology, Medical University Innsbruck, Innsbruck, Austria.

The supplementation of culture medium with fetal bovine serum (FBS, also referred to as "fetal calf serum") is still common practice in cell culture applications. Due to a number of disadvantages in terms of quality and reproducibility of in vitro data, animal welfare concerns, and in light of recent cases of fraudulent marketing, the search for alternatives and the development of serum-free medium formulations has gained global attention. Here, we report on the 3rd Workshop on FBS, Serum Alternatives and Serum-free Media, where regulatory aspects, the serum dilemma, alternatives to FBS, case-studies of serum-free in vitro applications, and the establishment of serum-free databases were discussed. The whole process of obtaining blood from a living calf fetus to using the FBS produced from it for scientific purposes is de facto not yet legally regulated despite the existing EU-Directive 2010/63/EU on the use of animals for scientific purposes. Together with the above-mentioned challenges, several strategies have been developed to reduce or replace FBS in cell culture media in terms of the 3Rs (Refinement, Reduction, Replacement). Most recently, releasates of activated human donor thrombocytes (human platelet lysates) have been shown to be one of the most promising serum alternatives when chemically-defined media are not yet an option. Additionally, new developments in cell-based assay techniques, advanced organ-on-chip and microphysiological systems are covered in this report. Chemically-defined serum-free media are shown to be the ultimate goal for the majority of culture systems, and examples are discussed.
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http://dx.doi.org/10.14573/altex.1705101DOI Listing
August 2018

A paradigm shift is needed to move biomedical research forward.

BMJ 2014 Jul 9;349:g4267. Epub 2014 Jul 9.

Dr Hadwen Trust, Suite 8, Portmill House, Hitchin SG5 1DJ, UK.

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http://dx.doi.org/10.1136/bmj.g4267DOI Listing
July 2014

Absolute oral bioavailability and metabolic turnover of β-sitosterol in healthy subjects.

Drug Metab Dispos 2012 Oct 23;40(10):2026-30. Epub 2012 Jul 23.

Unilever R&D, Vlaardingen, The Netherlands.

The metabolic turnover, absolute oral bioavailability, clearance, and volume of distribution for β-sitosterol were measured in healthy subjects. [(14)C]β-Sitosterol was used as an isotopic tracer to distinguish pulse doses from dietary sources and was administered by both oral and intravenous routes. The administered doses of [(14)C]β-sitosterol were in the region of 3 to 4 μg, sufficiently low as not to perturb the kinetics of β-sitosterol derived from the diet. Because the plasma concentrations of [(14)C]β-sitosterol arising from such low doses were anticipated to be very low, the ultrasensitive isotope ratio analytical method of accelerator mass spectrometry was used. The limit of quantification for [(14)C]β-sitosterol was approximately 0.1 pg/ml, the oral absolute bioavailability was just 0.41%, clearance was 85 ml/h, volume of distribution was 46 L, and the turnover was 5.8 mg/day. Given the steady-state concentrations of β-sitosterol (2.83 μg/ml), then the dietary load was calculated to be approximately 1400 mg/day.
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http://dx.doi.org/10.1124/dmd.112.046623DOI Listing
October 2012

The transcriptional programme of Salmonella enterica serovar Typhimurium reveals a key role for tryptophan metabolism in biofilms.

BMC Genomics 2009 Dec 11;10:599. Epub 2009 Dec 11.

Institute of Food Research, Norwich Research Park, Colney, Norwich, UK.

Background: Biofilm formation enhances the capacity of pathogenic Salmonella bacteria to survive stresses that are commonly encountered within food processing and during host infection. The persistence of Salmonella within the food chain has become a major health concern, as biofilms can serve as a reservoir for the contamination of food products. While the molecular mechanisms required for the survival of bacteria on surfaces are not fully understood, transcriptional studies of other bacteria have demonstrated that biofilm growth triggers the expression of specific sets of genes, compared with planktonic cells. Until now, most gene expression studies of Salmonella have focused on the effect of infection-relevant stressors on virulence or the comparison of mutant and wild-type bacteria. However little is known about the physiological responses taking place inside a Salmonella biofilm.

Results: We have determined the transcriptomic and proteomic profiles of biofilms of Salmonella enterica serovar Typhimurium. We discovered that 124 detectable proteins were differentially expressed in the biofilm compared with planktonic cells, and that 10% of the S. Typhimurium genome (433 genes) showed a 2-fold or more change in the biofilm compared with planktonic cells. The genes that were significantly up-regulated implicated certain cellular processes in biofilm development including amino acid metabolism, cell motility, global regulation and tolerance to stress. We found that the most highly down-regulated genes in the biofilm were located on Salmonella Pathogenicity Island 2 (SPI2), and that a functional SPI2 secretion system regulator (ssrA) was required for S. Typhimurium biofilm formation. We identified STM0341 as a gene of unknown function that was needed for biofilm growth. Genes involved in tryptophan (trp) biosynthesis and transport were up-regulated in the biofilm. Deletion of trpE led to decreased bacterial attachment and this biofilm defect was restored by exogenous tryptophan or indole.

Conclusions: Biofilm growth of S. Typhimurium causes distinct changes in gene and protein expression. Our results show that aromatic amino acids make an important contribution to biofilm formation and reveal a link between SPI2 expression and surface-associated growth in S. Typhimurium.
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http://dx.doi.org/10.1186/1471-2164-10-599DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2805695PMC
December 2009