We would like to welcome two new members to the lab – Elisabetta Ambron and Anupama Nair. Elisabetta Ambron is a post-doctoral fellow who received her Ph.D. at the University of Edinburgh, and was recently a post-doc at the University of Pennsylvania. She will be studying body representations, focusing on research with brain-damaged individuals. Anupama Nair is a new graduate student who received her B.A. at St. Xavier’s College and received her M.Sc. at the University of Amsterdam. After working on synesthesia and neuroimaging at the University of Michigan and UT-Dallas, she now begins her career as a graduate student in our lab.
We are very happy to announce that we’ve been awarded with a new NSF grant! In a collaboration with Jen Semrau (Kinesiology and Applied Physiology), Hyosub Kim (Physical Therapy) and Fabrizio Sergi (Biomedical Engineering), we plan to study proprioception and multisensory integration in stroke survivors. We will also use robotics and adaptive algorithms to develop individualized rehabilitation protocols for improving sensorimotor function.
We recently published a paper in Acta Psychologica with recent undergraduate Patrick Reyes and two collaborators at the University of Edinburgh, Elena Gherri and Nik Theodoropoulos. In it, we found novel evidence for an externally-based, hand-centered tactile Simon effect, and that it varied based on salience.
Two additional notes on this paper. First, this was our first preregistered paper, and all data and scripts can be found on OSF. Many thanks to Patrick for all his work on the analyses and maintaining the OSF site for this project. Preregistration was fun, and we’re looking forward to doing more of this. Second, this collaboration occurred by chance, as I saw Dr. Gherri giving a presentation on a very similar project. We thought this would be an excellent opportunity to join forces and collaborate, resulting in this paper and additional collaborations in the future.
Unfortunately, we have to say goodbye to our undergraduates who are leaving the lab after graduation. Patrick Reyes is moving on to Stanford to be an RA in Dr. Jeanne Tsai’s Culture and Emotion lab. Cathy Nadar is moving to Penn to start an RA position in Dr. Russell Epstein’s lab studying spatial navigation and scene perception. Finally, Julia Tortu is moving to NYC and taking a gap year. We are proud of all of your accomplishments, and will miss all of you!
We’ve just published a new paper in Cortex. Working with Steve Jax at Moss Rehab and H. Branch Coslett at the University of Pennsylvania, we report an interesting case of an individual with a small tumor resection in right posterior intraparietal sulcus (pIPS). First, we found that her deficit occurred for either limb and was only seen for targets left of fixation, suggesting that pIPS encodes reach locations in an eye-centered reference frame. Second, contrasting previous accounts of optic ataxia, we found that she was better at immediate versus delayed reaching. Finally, although she has no damage to occipital cortex, we found a clear perceptual deficit, as she was poor at detecting changes in stimulus position left of fixation.
Here’s a quick review of papers published in the lab over the last six months.
First, graduate student Yuqi Liu published a paper in Cognition, examining whether congruence in separate frames of reference contribute differently in multisensory integration. Using the mirror box, Yuqi had participants make synchronous or asynchronous tapping movements in the same or opposing postures, manipulating whether the movements were congruent or incongruent in an external frame of reference (i.e. movements going in the same direction) or a motor-based frame of reference (i.e. coordinated flexion/extension). She found increased illusory shift and more ownership of the mirror hand when movements were externally vs. motorically congruent, providing evidence that information re: crossmodal congruency is represented in different frames of reference. For more, see this Twitter thread.
Second, we’ve published two TMS papers with our collaborators at Penn. In a paper with Priyanka Shah-Basak published in Neuropsychologia, we presented participants with a task where participants had to judge whether a line was bisected centrally, or to the left/right of the line center. Importantly, these lines were presented centrally, or to the left/right of the viewer to separate the effects of TMS on viewer-centered or stimulus-centered processes. We found that TMS of right superior temporal gyrus (STG) disrupted performance resulting in additional errors in which participants reported that the right side of the line was longer (i.e. “neglecting” the left side of the line). Importantly, this was observed regardless of line position relative to the subject, suggesting that STG plays a role in stimulus-centered, but not viewer-centered processing.
In a separate TMS study with Elisabetta Ambron published in the Journal of Cognitive Neuroscience, we found that visual magnification of the hand influences motor evoked potentials using TMS. When seeing the hand magnified, we found larger MEPs for the magnified hand (but not the opposite, not magnified hand), and that more areas of motor cortex were active as a function of TMS stimulation.
Finally, in work with our collaborators at the University of Nevada-Reno, we published a review paper in Consciousness and Cognition on object shape and motion processing in human dorsal cortex.
A postdoctoral research position is now available in our lab. The postdoctoral researcher will take a lead role in designing and implementing cognitive neuroscience studies using the following techniques: functional neuroimaging, transcranial magnetic stimulation, research with brain-damaged individuals, and psychophysical/behavioral methods. Research topics include multisensory integration, action, touch, proprioception, plasticity, and body representations.
Our newly constructed Center for Biomedical and Brain Imaging houses a Siemens Prisma 3T MRI suite, TMS, EEG, fNIRS, eye trackers, and equipment for tactile and multisensory testing. We also have access to a large database of brain-damaged individuals who are active in research. Furthermore, the University of Delaware is located on the Northeast Corridor, within two hours of New York City, Philadelphia, Baltimore, and Washington, DC.
This position is fully funded by a multi-institutional grant from the National Science Foundation awarded to Dr. Jared Medina. The initial appointment is for one year, with potential for two additional years based on progress. The position is available now.
Applicants should have a Ph.D. in cognitive neuroscience or a related field. Applicants with expertise in fMRI, TMS, or cognitive neuropsychology are encouraged to apply. We also encourage individuals with a background in studying tactile perception, multisensory processing, plasticity, and/or body representations to apply as well. Review of applications will begin on Monday, February 12, and will continue until filled.
We strongly encourage potential applicants to contact Jared Medina (email@example.com) before applying. Candidates should submit a CV, research statement, and the names of three references through the University of Delaware Jobs website (click “Staff”, job #105227).
Our new paper in Cortex with Sam Cason, “No Evidential Value in Samples of tDCS Studies of Cognition and Working Memory in Healthy Populations“, uses a p-curve analysis to examine the strength of evidence in the tDCS literature. Briefly, a p-curve analysis is used to examine the distribution of significant p-values (p < .05) in a literature. If there is a real effect in the literature, the p-value distribution should be right-skewed, such that there are more p-values ranging from .00 to .01 compared to a bin ranging from .04 to .05. Interestingly, if there is no real underlying effect, the p-curve should be flat (i.e. an equal distribution of p-values in these bins). Furthermore, if someone is engaging in “questionable research practices”, this distribution may be left-skewed (more p-values from .04 to .05 vs. .00 to .01).
We used the p-curve analysis for two sets of studies in the tDCS literature. One was a random selection of tDCS studies on cognition, and the second was a set of tDCS studies on working memory taken from a recent meta-analysis. The p-value distribution from our sample of cognitive studies was not right-skewed, and our best estimate is that 8-16% of the studies from this sample would replicate. For the sample of working memory papers, our estimate is that 5% of the studies would replicate. We note that, given an α of .05, this is the same number of studies that would be expected to replicate if the data were randomly generated.
In the discussion, we note that these results do not mean that tDCS does not, or can not, influence cognitive processes. However, we are concerned that current practices in the general psychological literature (including small sample sizes, hypothesizing after the results are known, and multiple data analyses (the “garden of forking paths“) may lead to a literature with a low signal-to-noise ratio. Therefore, we strongly support preregistration of future tDCS studies, and replication of past tDCS studies, to better understand the relationship between brain stimulation and cognitive processing.
We’ve had several papers published from the lab over the last few months – what follows is a quick review.
First, we published a paper co-authored with former graduate student Catie Duckett in the Journal of Experimental Psychology: Human Perception & Performance titled “Domain-general biases in spatial localization: Evidence against a distorted body model hypothesis“. In it, we use evidence from a number of experiments to challenge the current hypothesis that our representation of the size and shape of our body is distorted. Instead, we demonstrate that these distortion effects are more likely due to domain-general biases in spatial memory.
Finally, Simon Fischer-Baum (Rice University) and I wrote a paper for an upcoming Special Issue of Cognitive Neuropsychology on “Theoretical and Methodological Issues for Twenty-First Century Cognitive Neuropsychology.” In our article, “Single case cognitive neuropsychology in the age of big data“, we discuss reasons for the perceived decline in cognitive neuropsychological research in the last twenty years, some perils in “big data” approaches that are being proposed for understanding cognitive processes, and then note how combining neural data and behavioral data from single case studies in brain-damaged individuals can further develop theories of mind and brain.
Our paper with Yuqi Liu (graduate student) is out in Scientific Reports. In it, we report a new version of the mirror box illusion. In it, participants place their hands in opposing postures (i.e. one hand palm down, the other hand palm up) in the mirror box and synchronously (or asynchronously) opened/closed their hands. In this condition, participants may see the reflection of their hand as palm up, while their actual hand (behind the mirror) is positioned palm down.
Interestingly, we found that for synchronous movements (when both hands opened/closed at the same time), participants reported feeling that the hand behind the mirror rotated, or “flipped” to match the position of their viewed hand. Importantly, the hand behind the mirror didn’t move – the perceived sensation was illusory.
We then examined whether biomechanical constraints of the “body schema” (i.e. how can the arm realistically rotate) influenced the strength of the illusion. For example, place your hands as in Figure d. below. Rotating your left hand to match the position of the right hand is relatively easy. Now do the same movement using the starting position in Figure e. Note how the movement is more constrained at the end – this is due to biomechanical constraints that limit our movement. We found that participants showed a stronger illusion for less constrained movements vs. more constrained movements – a surprising result given that there was no actual movement involved in the task.
In this illusion, we propose that its effectiveness is dictated, not only by well-known principles of multisensory integration, but also by knowledge about the configuration of our bodies. This illusion is quite easy to do, and we suggest trying it at home – it’s quite compelling.
If you want to learn more about the mirror box illusion, see the video below and the related article in UDaily.