EEG subject: KatSummer Research

Each summer, students and faculty carry-out collaborative research. In some cases students volunteer their time and assist faculty with ongoing projects or intiate their own novel lines of research. Students can also apply for summer research funding through various internal and external fellowship and granting agencies (see below). Finally, when funds are available, faculty may hire students to conduct summer research.

Funding

National Science Foundation (NSF)
Reed College Science Research Fellowship
Wender Fellowship for Collaborative Research in Psychology
Opportunity Fellowship
Opportunity Grant
Initiative Grant
President's Summer Fellowship
Summer Internship Award

Previous Summer Research Awards

2018

Andrew Kyroudis

Isolating the neural correlates of conscious vision via pattern masking and EEG
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Abstract

The proposed experiment uses pattern masking to modulate visibility of line drawings, using both report and no-report paradigms to isolate the neural correlates of conscious visual perception from the neural correlates of reporting about conscious visual perception. Pattern masking is a way of sequentially presenting series of stimuli (with precise timing) such that conscious visual perception can be altered purely by stimulus timing. Here, modulating conscious visual perception simply means modulating the visibility of a percept. “Did you see it or not?” – this is the ubiquitous question we hope to answer with neural data in the proposed experiment. Scalp electroencephalography (EEG) recordings and event-related potentials (ERPs) in human subjects will be used to track the moment-by-moment activity of populations of neurons associated with generating conscious visual experience.

Anton Lydia Lutsyshyna

Distinguishing perceptual experience from its report: A brain recording experiment
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Abstract

The study of the neural basis of consciousness is relatively novel compared to other scientific pursuits. Due to the complexity of the problem, many researchers in the field have adopted a simplified approach in which the initial goal is to identify neural correlates of basic conscious experiences, such as seeing a picture. Various techniques are now available to present an identical visual stimulus that is sometimes consciously seen and other times unconsciously processed by the visual system. By contrasting these two carefully controlled conditions, it is possible to isolate brain activity associated with conscious perception while keeping sensory input constant. Based on this method, two main categories of theories have arisen: “sensory theories” and “cognitive theories” of consciousness. Such theories make distinct predictions about the timing and neuroanatomical locations of the neural correlates of conscious vision. To test these theories, the proposed study uses a “no-report paradigm” along with electroencephalogram (EEG) recordings to isolate neural activity related to conscious vision from neural activity related to reporting what one has just seen. We expect to find that a brainwave previously thought to index conscious perception (P3b) is in fact a signifier of reporting an experience; not of having the experience. Such a result would challenge cognitive theories and support sensory theories of consciousness. Alternatively, if we find the P3b wave in the no-report condition, cognitive theories would be supported. This general line of research has implications for basic science, clinical detection of consciousness in patients, and diagnosis/treatment of disorders of consciousness.

2017

James Glass

Auditory awareness of sine-wave speech
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Abstract

Sine-wave speech (SWS) stimuli are computer-generated speech patterns that are consciously perceived as speech only after participants are cued into the speech content. Comparing brain activity elicited by SWS before and after the speech content is perceived may provide a unique window into the neural basis of conscious speech perception. The current proposal seeks to investigate these neural differences through EEG measurements combined with a novel 3-phase study design. In this design, participants are unaware of the speech components of SWS stimuli in phase 1, aware of the speech components in phase 2, and aware and performing a task on the speech components in phase 3. By comparing the EEG differences between the processing of the SWS stimuli and carefully designed control stimuli across the 3 phases of the experiment, we hope to identify neural correlates of conscious speech perception and separate these from neural correlates of post-perceptual task-related processes. Results from this study could potentially inform two competing theories of consciousness, Victor Lamme’s “recurrent processing theory” and Stanislas Dehaene’s “global neuronal workspace theory”. Because most studies of conscious perception involve visual stimuli, this auditory experiment also has the potential to inform the debate between domain-general and domain-specific theories of conscious perception.

Camille Hendry and Aoife Hough

Grapheme-color synesthesia in visual search
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Abstract

Grapheme-color synesthesia is a condition in which affected individuals experience consistent associations between graphemes (letter or numbers) and colors. In previous research done at Reed College’s SCALP Lab it was found that, compared with control participants, people with grapheme-color synesthesia had shorter response times (RTs) and shorter latency and larger amplitude N2pc in a visual search task using achromatic displays (black graphemes on white background). The N2pc is a well-known neural marker of selective attention. These findings suggested that synesthetes were using their experience of color to guide their attention and speed up their visual search. To confirm this, a second experiment showed that control participants presented with colored vs. achromatic graphemes show a similar advantage to that observed in synesthetes vs. controls. However, there is still the possibility that synesthetes may have a general advantage in speed of processing that is independent of their synesthetic color experience. The current proposal seeks to investigate whether the observed synesthetic advantage in visual search tasks extends to stimuli other than English graphemes. Synesthetes and non-synesthetes will perform a visual search task in three conditions: Georgian graphemes (unfamiliar graphemes), stick figures (non-graphemes), and English graphemes (familiar graphemes). The expected result is that synesthetes will only show an advantage (shorter RT and earlier/larger N2pc) in the familiar grapheme condition. This result would demonstrate that the synesthetic advantage is due to the color-grapheme associations formed with familiar graphemes and not to another undefined ability of synesthetes to perform better on any visual search task.

2016

Jasmine Huang

Language and color perception: An electrophysiological investigation

2015

Hannah Baumgartner

Effect of spatial attention on early visual processing in the primary visual cortex
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Abstract

The present study aimed to examine whether spatial attention can modulate visual processing at the earliest cortical level of sensory processing. While it is well known that attention can selectively modify visual processing, the cutoff for where in the neural pathway this effect first manifests has been the topic of intense debate. Many studies find that the initial phase of processing in primary visual cortex (40-60 msec poststimulus onset) is unaffected by attention. This suggests a rich detailed cortical representation of the visual world, at least during initial stages of sensory processing. A handful of recent experiments, however, suggest that spatial attention can selectively modulate processing as early as 40-60 msec in primary visual cortex (V1). The present study aimed to replicate and extend one of the most promising experiments that finds early attentional effects on sensory processing in V1 [1]. Subjects performed a visuospatial attention task while electrophysiological brain activity was recorded via scalp EEG. Importantly, stimulus locations and electrode positions were customized for each individual subject in order to account for variations in electrical signal strength due to neuroanatomical differences. Preliminary results suggest that spatial attention does not influence visual processing at this early level, though more data collection is required to confirm this finding.

Hayley VanderJagt

Interpreting contradictory adjective sequences via the recording of brain activity: "When big dogs are also small."
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Abstract

This study intended to investigate the nature of processing of multiple adjectives via the recording of brain activity elicited by sentences containing contradictory sequences that appear to violate grammatical-semantic constraints (e.g. “the small big dog chased the ball”). In a prior study using similar sentences, Kemmerer et. al. (2007) found a reduced N400 and an enhanced P600 at the 2nd adjective (e.g. big) proposing that these effects reflect semantic and syntactic aspects of a temporary reanalysis. Our study tested this proposal by presenting 3 types of contexts containing high, low, or no licensing information prior to the critical sentence. If Kemmerer et. al. are correct, we proposed that the P600 and N400 effects should disappear or decrease considerably when sentences follow licensing (high information) contexts. In contrast, if the effects remained, alternative accounts based on a syntactic-semantic reanalysis would be supported. Our study also introduced a broader range of adjective types than Kemmerer et al., to explore whether the N400/P600 effects are a general effect of contradictory adjectives or whether this is an effect of the relative interpretation of dimension adjectives (e.g. big/small).

2014

Fenner Macrae

The role of abstract beliefs and neural oscillations in motor preparation and inhibition
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Abstract

The present study is a replication and extension of a recent experiment by Rigoni et al. (2011)
which found that inducing disbelief in free will alters brain activity associated with preconscious motor
preparation. This finding is surprising because an abstract belief appears to have affected low-level
neural activity in the pre-motor cortex. The current study will help to determine whether this finding is
genuine by replicating the procedures and analyses of the original study. We will also investigate
whether pre-existing beliefs concerning free will influence brain activity in a similar manner to induced
beliefs. In a separate experiment Rigoni et al. (2012) found that inducing disbelief in free will lowered
subjects' propensity to inhibit prepared motor responses. In the present study, we will examine neural
correlates of aborting a planned motor action to determine whether Rigoni et al.’s (2012) behavioral
observation corresponds to a difference in neural oscillatory activity previously associated with motor
inhibition.

Angelynn Khoo

Functional significance of motor activation during language processing
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Abstract

The present study aims to investigate the functional role of activation in motor-related brain areas during language processing in intact individuals by recording brain activity elicited by action-related noun-verb phrases. Particularly, we aim to address one key question: whether motor activation reflects primarily the automatic activation of lexical-semantic features (Pulvermuller, 2005) or is instead a sign of post-lexical motor imagery (Toni et al., 2008).

2013

Christian Graulty

Electrophysiological dynamics of cross-modal neuroplasticity
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Abstract

The present study aims to investigate brain plasticity in intact individuals by recording brain activity elicited by auditory ‘soundscapes’ before and after undergoing sensory substitution training. Such training allows subjects to extract shape information from auditory stimuli. The success of the sensory substitution procedure will be assessed in a task using novel sounds to identify novel shapes. We aim to examine the time course of lateral occipital complex activity in shape processing and assess how it is modulated by cross-modal neuroplasticity.

Enriqueta Canseco-Gonzalez

Electrophysiological dynamics of cross-modal plasticity in the lateral occipital complex due to sensory substitution training
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Abstract

We investigate brain plasticity in intact individuals by recording their brain activity elicited by auditory ‘soundscapes’ before and after undergoing sensory substitution training. Such training allows subjects to extract shape information from auditory stimuli. The success of the sensory substitution procedure will be assessed in a task using novel sounds to identify novel shapes. We hope to demonstrate the time course of lateral occipital complex activity in shape processing (regardless of modality) and assess how it is modulated by cross-modal plasticity.

2012

Kathryn Schelonka

Electrophysiological correlates of conscious speech perception
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Abstract

Previous studies have suggested that linguistic information is processed differently from non-linguistic sounds at early and late stages of auditory perception; however, the neural mechanisms responsible for discrimination between speech and non-speech sounds have been notoriously difficult to identify due to the physical acoustic differences between speech and non-speech stimuli.  Sine-wave speech (SWS) is a unique auditory phenomenon in which the same physical stimulus can be perceived as noise or as speech depending on perceptual expectations.  In this study we compared event-related potentials (ERPs) elicited by SWS stimuli in both non-speech and speech conditions. Participants completed a discrimination task between four SWS sounds before and after they had been trained to hear the sounds as speech.  We found that the N1 auditory component was larger in the non-speech condition, likely reflecting increased attentional demands for the more difficult task of sound discrimination compared to speech discrimination.  The speech and non-speech elicited ERPs also diverged around 300 ms over the frontal scalp, resulting in a lasting positive shift in the speech condition compared to the non-speech condition.  This latter difference may reflect upper-level speech processes.  Follow-up studies controlling for task difficulty and word repetition will also be discussed.

Loretta Yiu

An electrophysiological study on the time course of bilingual word recognition
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Abstract

Current theories of monolingual language comprehension suggest that phonological processing precedes semantic information, which in turn precedes syntactic information.  Bilingual language comprehension likely requires an additional level: knowledge of which language a specific word belongs to.  The Revised Bilingual Interactive Activation (BIA+) model of word recognition proposes that bilinguals use language ‘tags,’ that is, information identifying the specific language of a word, to help them monitor the appropriate language of use at any given time (Dijkstra & van Heuven, 2002).  A central question then is when exactly this language ‘tag’ information becomes available during language comprehension.  Using the recording of event-related potentials, we investigated the time course of semantic and language ‘tag’ encoding during visual word recognition.  Spanish-English bilinguals viewed a series of printed words while making dual-choice go/nogo and left/right hand decisions based on semantic (whether the word was an object or an animal) and language ‘tag’ information (whether the word was in English or Spanish).  According to initial findings, the onset latency of the N200 (a component related to response inhibition) indicated that language ‘tag’ information may be accessed as early as semantic information or soon after. This finding is compatible with the BIA+ model, supporting the claim that language ‘tag’ information is accessed relatively late (i.e. compared to phonological information) during bilingual word recognition. That is, the language ‘tag’ information may come too late to filter out words inappropriate to the current language context.