Verifiability and Action verb Processing: An ERP Investigation 1 1  Verifiability and Action verb Processing: An ERP Investigation Sean C. Thomas 1, Trevor Brothers 2, David Vares 1, Joël Dickinson1 1 2 Word Lists ERP Recording 64-electrode HydroCel Geodesic Sensor Net (Electrical Geodesics, Inc., Eugene, OR). Data acquisition was done using NetStation software, version 4.4.1 (Electrical Geodesics, Inc., Eugene, OR) and digitized with a sampling rate of 250 Hz, using the vertex as reference electrode. Data were re-referenced off-line to the average mastoid reference. EEG data was filtered on-line using a 0.1 Hz highpass filter and stored on a computer for off-line analysis. ERP data were filtered off-line using a 0.3-30 Hz bandpass filter and segmented into 1200 msec epochs which were sorted by stimulus type (Verifiable product, non-verifiable products). Epochs began 200 msec before stimulus onset and extended 1000 msec after the appearance of the stimulus. Using NetStation v.4.4.1 (Electrical Geodesics, Inc., Eugene, OR), data were examined for artifacts using an eye-blink threshold of 100μV and a threshold of 5μV for horizontal eye movements, and were visually checked afterwards. An average was calculated for each subject and epochs were baseline-corrected using the 200 msec interval before stimulus onset. A grand average across all participants was then calculated for analysis. Procedure   Participants were tested individually in a sound proof booth. Each testing session took ~45 minutes to perform. A total of 56 stimuli were presented in each trial block for a total of 3 blocks with breaks in between. Stimuli were completely randomized within each block. An example of a trial list is below: We did the behavioural analysis first and after we realized that 3 in the erp didn’t have enough good segments- so they’re removed. Fix the intro to make sure it’s referencing the right numbers in the references section. Abstract Results: Behavioural Discussion The semantic meaning of verifiable action verbs (‘throw’), is encoded along with the action associated with it and is thought to result from associative learning. Mental action verbs (‘perceive’), (verbs with no externally verifiable products) theoretically would be learned differently. Yet it has been found that people respond similarly when the verbs are embedded in a common instruction of a response time task and size discrimination task. The purpose of the current study was to investigate associative learning theory in relation to mental action verbs compared to verifiable action verbs. Significant behavioural differences and differences in ERP data were found. Response time F(1,23)=5.22, p<.05, η2 = .18 ERP differences were observed between the two verb categories with greater amplitude for the eye related verbs in the occipital region and greater amplitude for the mouth related verbs in the parietal region, particularly earlier on. There is initial evidence suggesting that non-verifiable verbs are ‘categorized’ in a similar fashion to verifiable verbs in that, the region responsible for performing the action is activated along with the retrieval of the word itself. Moreover response time differences indicate faster response times for mouth-related verifiable verbs than eye-related nonverifiable verbs , a finding that is consistent according to Pulvermuller’s findings regarding RT differences between leg related, arm related and face related verbs. Future research will compare activation between different types of nonverifiable verbs. For example, auditory verbs and vision verbs such as hear vs. look. Introduction Research on action verbs has shown that semantic meaning of the verbs is encoded along with the action associated with it (Pulvermuller, 2001) and this is thought to result from associative learning (e.g. when we learn the word ‘throw’ it is often accompanied with the movement of throwing). Mental action verbs (i.e. verbs with no externally verifiable products) theoretically would be learned in a different way. For example, it is impossible to observe the action associated with someone else ‘perceiving’. The question as to whether people have a common understanding of these mental action verbs was explored by Dickinson and Szeligo (2008). It has been found that people respond similarly when the verbs were embedded in a common instruction of a response time task and size discrimination task. However, Pulvermuller et al. (2001) have shown that arm related verbs vs. face related verbs vs. leg related verbs are processed in different regions of the brain as well as show differences in event related potential and behavioural data. The goal of the present study was to find out if vision verbs without verifiable products such as ‘perceive’ have a similar brain activation pattern to verbs with verifiable products such as ‘shout’, ‘whisper’, etc. Knowing whether or not the occipital lobe is activated along with word retrieval in the case of visual verbs without verifiable products will give us insight into how the verbs are characterized semantically and also about how they might be learned. ·         Accuracy  No significant differences in percentage of accurate responses were found between verifiable verbs (97.6%) and non-verifiable verbs (98.7%). Results: ERP 400-500ms (Verb X Montage) F(1,19)= 2.94, p=.10 800-1000ms (Verb X Montage) F=2.68, p=.12 , η 2 = .12 For occipital, F(1,19)=3.809, p=.066 400-500ms F(1, 19)=.11, p=.75 800-1000ms F(1,19)=2.65, p=.12 Methods Participants   20 participants (3 males) participated in the experiment. The age varied between 18 to 42 (mean=20.9; standard deviation = 4.9). All participants were undergraduate students with normal or corrected-to-normal vision and no history of neurological illness or drug abuse. They all spoke English as their first language. Informed consent was obtained from all of the participants. References Cacciari, C., Levorato, M.C. (2000). The semantic structure of vision verbs: A psycholinguistic investigation of Italian. European Journal of Cognitive Psychology, 12, 87-106. Dickinson, J., & Szeligo, F. (2008). Impact of mental operation instructions. Canadian Journal of Experimental Psychology/Revue Canadienne De Psychologie Expérimentale, 62(4), 211-222. Pulvermuller, F., Harle, M., Hummel, F., (2001). Walking or Talking? Behavioural and nuerophysiological correlates of action verb processing. Brain and language, 78, 143-168.