This work was supported by Academy of Finland, grant numbers [259952, 276643]. We would like to thank Mikko Sams for the supervision and Enrico Glerean, Jussi Alho, Anna &#196;im&#228;l&#228; for helping with the data, Johan West&#246; for helping with the visualization as well as Marita Kattelus and Toni Auranen from Advanced Magnetic Imaging (AMI) Centre, Aalto NeuroImaging, Aalto University, Espoo, Finland for their help and support.

The protocol was approved by the Aalto University Research Ethics Committee.
1. Participant screening and preparation
<ol>
	<li>Match the different groups of recruited participants (here, heterosexual and homosexual groups) according to age, handedness, and level of education. Ensure that all participants can fully comprehend the language of the movie and feel comfortable watching it without subtitles. Alternatively, consider screening a movie in the native tongue of participants.
	<ol>
		<l...

<ol>
	<li>Bar, M., Neta, M., Linz, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Very+first+impressions.">Very first impressions.</a> Emotion. 6 (2), 269-278 (2006).</li><li>Ballew, C. C., Todorov, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Predicting+political+elections+from+rapid+and+unreflective+face+judgments.">Predicting political elections from rapid and unreflective face judgments.</a> Proceedings of the National Academy of Sciences of the United States of America. 104 (46), 17948-17953 (2007).</li><li>Porter, S., England, L., Juodis, M., ten Brinke, L., Wilson, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Is+the+face+a+window+to+the+soul?+Investigation+of+the+accuracy+of+intuitive+judgments+of+the+trustworthiness+of+human+faces.">Is the face a window to the soul? Investigation of the accuracy of intuitive judgments of the trustworthiness of human faces.</a> Canadian Journal of Behavioural Science. 40 (3), 171-177 (2008).</li><li>Borkenau, P., Brecke, S., M&#246;ttig, C., Paelecke, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Extraversion+is+accurately+perceived+after+a+50-ms+exposure+to+a+face.">Extraversion is accurately perceived after a 50-ms exposure to a face.</a> Journal of Research in Personality. 43 (4), 703-706 (2009).</li><li>Rule, N. O., Ambady, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=She's+Got+the+Look:+Inferences+from+Female+Chief+Executive+Officers'+Faces+Predict+their+Success.">She's Got the Look: Inferences from Female Chief Executive Officers' Faces Predict their Success.</a> Sex Roles. 61 (9-10), 644-652 (2009).</li><li>Todorov, A., Pakrashi, M., Oosterhof, N. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluating+Faces+on+Trustworthiness+After+Minimal+Time+Exposure.">Evaluating Faces on Trustworthiness After Minimal Time Exposure.</a> Social Cognition. 27 (6), 813-833 (2009).</li><li>Todorov, A., Loehr, V., Oosterhof, N. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Obligatory+Nature+of+Holistic+Processing+of+Faces+in+Social+Judgments.">The Obligatory Nature of Holistic Processing of Faces in Social Judgments.</a> Perception. 39 (4), 514-532 (2010).</li><li>Hart, A. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differential+response+in+the+human+amygdala+to+racial+outgroup+vs+ingroup+face+stimuli.">Differential response in the human amygdala to racial outgroup vs ingroup face stimuli.</a> Neuroreport. 11 (11), 2351-2355 (2000).</li><li>Phelps, E. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Performance+on+Indirect+Measures+of+Race+Evaluation+Predicts+Amygdala+Activation.">Performance on Indirect Measures of Race Evaluation Predicts Amygdala Activation.</a> Journal of Cognitive Neuroscience. 12 (5), 729-738 (2000).</li><li>Cunningham, W. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Separable+Neural+Components+in+the+Processing+of+Black+and+White+Faces.">Separable Neural Components in the Processing of Black and White Faces.</a> Psychological Science. 15 (12), 806-813 (2004).</li><li>Avenanti, A., Sirigu, A., Aglioti, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Racial+Bias+Reduces+Empathic+Sensorimotor+Resonance+with+Other-Race+Pain.">Racial Bias Reduces Empathic Sensorimotor Resonance with Other-Race Pain.</a> Current Biology. 20 (11), 1018-1022 (2010).</li><li>Kubota, J. T., Banaji, M. R., Phelps, E. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+neuroscience+of+race.">The neuroscience of race.</a> Nature Neuroscience. 15 (7), 940-948 (2012).</li><li>Freeman, J. B., Johnson, K. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=More+Than+Meets+the+Eye:+Split-S+Social+Perception.">More Than Meets the Eye: Split-S Social Perception.</a> Trends in Cognitive Sciences. 20 (5), 362-374 (2016).</li><li>Bagnis, A., Celeghin, A., Mosso, C. O., Tamietto, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Toward+an+integrative+science+of+social+vision+in+intergroup+bias.">Toward an integrative science of social vision in intergroup bias.</a> Neuroscience and Biobehavioral Reviews. 102, 318-326 (2019).</li><li>Brown, R., Hewstone, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+integrative+theory+of+intergroup+contact.">An integrative theory of intergroup contact.</a> The Social Psychology of Intergroup Relations. , 255-343 (2005).</li><li>Meeren, H. K. M., van Heijnsbergen, C. C. R. J., de Gelder, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+perceptual+integration+of+facial+expression+and+emotional+body+language.">Rapid perceptual integration of facial expression and emotional body language.</a> Proceedings of the National Academy of Sciences of the United States of America. 102 (45), 16518-16523 (2005).</li><li>Ewbank, M. P., Fox, E., Calder, A. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+interaction+between+gaze+and+facial+expression+in+the+amygdala+and+extended+amygdala+is+modulated+by+anxiety.">The interaction between gaze and facial expression in the amygdala and extended amygdala is modulated by anxiety.</a> Frontiers in Human Neuroscience. 4, 56 (2010).</li><li>Schwarz, K. A., Wieser, M. J., Gerdes, A. B. M., M&#252;hlberger, A., Pauli, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Why+are+you+looking+like+that?+How+the+context+influences+evaluation+and+processing+of+human+faces.">Why are you looking like that? How the context influences evaluation and processing of human faces.</a> Social Cognitive and Affective Neuroscience. 8 (4), 438-445 (2013).</li><li>Righart, R., de Gelder, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recognition+of+facial+expressions+is+influenced+by+emotional+scene+gist.">Recognition of facial expressions is influenced by emotional scene gist.</a> Cognitive, Affective, and Behavioral Neuroscience. 8 (3), 264-272 (2008).</li><li>Mumenthaler, C., Sander, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Social+appraisal+influences+recognition+of+emotions.">Social appraisal influences recognition of emotions.</a> Journal of Personality and Social Psychology. 102 (6), 1118-1135 (2012).</li><li>Wieser, M. J., Brosch, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Faces+in+context:+A+review+and+systematization+of+contextual+influences+on+affective+face+processing.">Faces in context: A review and systematization of contextual influences on affective face processing.</a> Frontiers in Psychology. 3, (2012).</li><li>O'Toole, A. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recognizing+people+from+dynamic+and+static+faces+and+bodies:+Dissecting+identity+with+a+fusion+approach.">Recognizing people from dynamic and static faces and bodies: Dissecting identity with a fusion approach.</a> Vision Research. 51 (1), 74-83 (2011).</li><li>Hasson, U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intersubject+Synchronization+of+Cortical+Activity+During+Natural+Vision.">Intersubject Synchronization of Cortical Activity During Natural Vision.</a> Science. 303 (5664), 1634-1640 (2004).</li><li>Malinen, S., Hlushchuk, Y., Hari, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Towards+natural+stimulation+in+fMRI-Issues+of+data+analysis.">Towards natural stimulation in fMRI-Issues of data analysis.</a> NeuroImage. 35 (1), 131-139 (2007).</li><li>J&#228;&#228;skel&#228;inen, I. P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inter-Subject+Synchronization+of+Prefrontal+Cortex+Hemodynamic+Activity+During+Natural+Viewing.">Inter-Subject Synchronization of Prefrontal Cortex Hemodynamic Activity During Natural Viewing.</a> The Open Neuroimaging Journal. 2 (1), 14-19 (2008).</li><li>Wilson, S. M., Molnar-Szakacs, I., Iacoboni, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Beyond+superior+temporal+cortex:+Intersubject+correlations+in+narrative+speech+comprehension.">Beyond superior temporal cortex: Intersubject correlations in narrative speech comprehension.</a> Cerebral Cortex. 18 (1), 230-242 (2008).</li><li>Lahnakoski, J. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synchronous+brain+activity+across+individuals+underlies+shared+psychological+perspectives.">Synchronous brain activity across individuals underlies shared psychological perspectives.</a> NeuroImage. 100, 316-324 (2014).</li><li>Saarim&#228;ki, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Discrete+Neural+Signatures+of+Basic+Emotions.">Discrete Neural Signatures of Basic Emotions.</a> Cerebral Cortex. 26 (6), 2563-2573 (2016).</li><li>Bacha-Trams, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differential+inter-subject+correlation+of+brain+activity+when+kinship+is+a+variable+in+moral+dilemma.">Differential inter-subject correlation of brain activity when kinship is a variable in moral dilemma.</a> Scientific Reports. 7 (1), 14244 (2017).</li><li>Hall, A. E., Bracken, C. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=I+really+liked+that+movie.">I really liked that movie.</a> Journal of Media Psychology. 23 (2), 90-99 (2011).</li><li>Hasson, U., Landesman, O., Knappmeyer, B., Vallines, I., Rubin, N., Heeger, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neurocinematics:+The+Neuroscience+of+Film.">Neurocinematics: The Neuroscience of Film.</a> Projections. 2 (1), 1-26 (2008).</li><li>Greenwald, A. G., McGhee, D. E., Schwartz, J. L. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measuring+individual+differences+in+implicit+cognition:+The+implicit+association+test.">Measuring individual differences in implicit cognition: The implicit association test.</a> Journal of Personality and Social Psychology. 74 (6), 1464-1480 (1998).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> MHRA Safety guidelines for MRI equipment in clinical use. 3, 104 (2007).</li><li>Afdile, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Contextual+knowledge+provided+by+a+movie+biases+implicit+perception+of+the+protagonist.">Contextual knowledge provided by a movie biases implicit perception of the protagonist.</a> Social Cognitive and Affective Neuroscience. 14 (5), 519-527 (2019).</li><li>Dal Cin, S., Zanna, M. P., Fong, G. T., Knowles, E. S., Linn, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Narrative+persuasion+and+overcoming+resistance+BT+-+Resistance+to+persuasion.">Narrative persuasion and overcoming resistance BT - Resistance to persuasion.</a> Resistance to persuasion. , 175-191 (2004).</li><li>Wheeler, S. C., Green, M. C., Brock, T. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fictional+narratives+change+beliefs:+Replications+of+Prentice,+Gerrig,+and+Bailis+(1997)+with+mixed+corroboration.">Fictional narratives change beliefs: Replications of Prentice, Gerrig, and Bailis (1997) with mixed corroboration.</a> Psychonomic Bulletin and Review. 6 (1), 136-141 (1999).</li><li>Green, M. C., Brock, T. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+transportation+in+the+persuasiveness+of+public+narratives.">The role of transportation in the persuasiveness of public narratives.</a> Journal of Personality and Social Psychology. 79 (5), 701-721 (2000).</li><li>Wang, J., Calder, B. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Media+Transportation+and+Advertising.">Media Transportation and Advertising.</a> Journal of Consumer Research. 33 (2), 151-162 (2006).</li><li>Green, M. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transportation+Into+Narrative+Worlds:+The+Role+of+Prior+Knowledge+and+Perceived+Realism.">Transportation Into Narrative Worlds: The Role of Prior Knowledge and Perceived Realism.</a> Discourse Processes. 38 (2), 247-266 (2004).</li><li>Schulenberg, S. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Psychotherapy+and+Movies:+On+Using+Films+in+Clinical+Practice.">Psychotherapy and Movies: On Using Films in Clinical Practice.</a> Journal of Contemporary Psychotherapy. 33 (1), 35-48 (2003).</li></ol>

This paper outlines the novel method for investigating the implicit brain using a post-movie subliminal measurement referred to as PMSM. In a recently published study, this method has shown that 1) implicit brain response is dynamic and 2) there is continuous learning from the social environment as well as formulation of judgment based on contextual knowledge (and not solely based on facial characteristics). Therefore, the proposed PMSM method can provide an alternative to the classical method when investigating implicit...

Recent studies show that initial social judgment becomes formulated within the first 32&#8211;100 ms of meeting another person1,2,3,4,5,6,7. Subliminal presentation of faces has been used extensively to investigate implicit biases towards different ethnic and racial groups (e.g., by presenting Caucasian American and African American faces that differ in skin color to subjects from both groups)8,9,10,11,12,13,14. However, social groups are also characterized by factors other than physical facial characteristics15.
Facial perception has been shown to be highly sensitive to contextual cues (i.e., body posture16, eye-gaze direction of the face17, a priori knowledge about the face18, visual background of the presented face19, presentation of the face separately or with other faces20). These factors can all affect facial perception. Weiser and Brosch21, in their extensive review, suggested to investigate facial perception in more naturalistic settings by ensuring that laboratory experiment is similar to real-life environments. Indeed, even simple tasks, such as recognizing people, have been shown to be more accurate when presented with video footage closer to real-life perception than when using static images22.
During the last several decades, brain imaging studies have proven that video clips can be successfully used to study realistic social perception23,24,25,26,27,28,29. The presented method is based on results from these studies and additional findings demonstrating that movie narratives can temporarily transport viewers to the world of a protagonist30. The protocol combines movie viewing with subliminal stimulus presentation as an alternative method to investigate implicit social bias formation under naturalistic conditions.
The protocol for this novel approach, post-movie subliminal measurement (PMSM), is presented here. When watching a socially engaging movie, the spectator gains knowledge about the protagonist and becomes familiar with his/her identity and world views. In contrast with other narrative art forms, movies are unique in that they present a compelling, rich, and complex story over a short time period. Furthermore, audiovisual and cinematic properties of movies synchronize brain activity across spectators23,25,29,31. Thus, it is helpful to ensure that subjects are presented with the information in a considerably similar way.
The PMSM method shows that when the face of a protagonist is presented subliminally after the movie (vs. before), implicit neural responses are successfully evoked. These responses depend on knowledge that the viewer gains about the protagonist&#39;s character with respect to his/her implicit social views. As there is a vast number of movies available that depict a variety of social characters, the PMSM method enables investigation of the brain&#39;s complex implicit views in a manner that is close to real-life social perceptions.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>3T Siemens MAGNETOM Skyra</td>
			<td>Siemens Healthcare, Erlangen, Germany</td>
			<td></td>
			<td>MRI device, using a standard 20-channel receiving head-neck coil</td>
		</tr>
		<tr>
			<td>Avid Media Composer</td>
			<td><a href="https://www.avid.com/media-composer" target="_blank">https://www.avid.com/media-composer</a></td>
			<td></td>
			<td>Video editing software used to create the stimuli.</td>
		</tr>
		<tr>
			<td>EAR-tip</td>
			<td>Etymotic Research, ER3, IL, USA</td>
			<td></td>
			<td>Earplugs compatible for MRI</td>
		</tr>
		<tr>
			<td>FSL software</td>
			<td><a href="https://www.win.ox.ac.uk/" target="_blank">https://www.win.ox.ac.uk/</a>, version 5.0.9</td>
			<td></td>
			<td>Software used to analyse the data.</td>
		</tr>
		<tr>
			<td>Panasonic PT-DZ110X projector</td>
			<td>Panasonic Corporation, Osaka, Japan</td>
			<td></td>
			<td>The stimuli were back-projected on a semitransparent screen</td>
		</tr>
		<tr>
			<td>Presentation software</td>
			<td>Neurobehavioral Systems Inc., Albany, California, USA</td>
			<td></td>
			<td>Software used to present stimuli during the fMRI scan</td>
		</tr>
		<tr>
			<td>Sensimetrics S14 insert earphones</td>
			<td>Sensimetrics Corporation, Malden, Massachusetts, USA</td>
			<td></td>
			<td>Auditory stimulation was delivered through Sensimetrics S14 insert earphones</td>
		</tr>
	</tbody>
</table>

post-movie subliminal measurement (pmsm), for investigating implicit social bias

New knowledge is continuously gained from a social environment that can influence how people respond to each other. Such responses often occur implicitly, at a subliminal perceptual level, and related brain mechanisms can be experimentally isolated by presenting the stimuli quickly. Subliminal presentation of faces that belong to different ethnicity groups, races, or gender has been shown to be successful in investigating social implicit responses. However, many implicit responses are based on knowledge previously gained about the faces (e.g., sexual orientation, political views, and socioeconomic status) and not solely on physical appearance. Here, a novel method called post-movie subliminal measurement (PMSM) is presented. When watching a socially engaging movie, a spectator gains knowledge about the protagonist and becomes familiar with his/her identity and world views. When the face of the protagonist is presented subliminally after the movie, it evokes an implicit neural response depending on what is learned about the protagonist. With a vast number of movies available, each depicting a variety of people with different identities, the PMSM method enables investigation of the brain&#39;s complex implicit biases in a manner that resembles real-life social perceptions.

Presented here are some results using PMSM from the published article by Afdile et al.34. Here, implicit bias was investigated among homosexual and heterosexual subjects (15 heterosexuals, 14 homosexuals) toward the protagonist after realizing he is homosexual in the movie, making him an &#34;ingroup&#34; to the homosexual participants and &#34;outgroup&#34; to the heterosexual participants. In line with our IAT results, this factor was shown to be significant in both groups, in which the heterose...

Watch this Scientific Journal Video about Post-Movie Subliminal Measurement PMSM, for Investigating Implicit Social Bias at JoVE.com

Post-Movie Subliminal Measurement PMSM, for Investigating Implicit Social Bias

This protocol describes the use of movies to investigate brain mechanisms underlying implicit social biases during functional magnetic resonance imaging. When the face of a protagonist is presented after a movie subliminally, it evokes an implicit response based on knowledge of the protagonist gained during the movie.

Post-Movie Subliminal Measurement (PMSM), for Investigating Implicit Social Bias

New knowledge is continuously gained from a social environment that can influence how people respond to each other. Such responses often occur implicitly, ...

Post-movie subliminal measurement can help answer key questions in understanding the neuro-processing underlying social perception, such as how contextual knowledge bias our implicit response toward others. Implicit bias is a very challenging phenomenon to investigate. By presenting stimuli for very brief periods of time, one can measure the implicit response of the brain that perceives conscious processing.In our new paradigm, we are presenting movies to experimental subjects to shape their implicit bias. This can be relevant to researchers who are interested in investigating social perception and implicit bias amongst social groups that cannot be differentiated based on their appearances, such as political groups, religious groups, groups with different sexual orientation, and more. The following protocol will be demonstrated by Marita Kattelus and Johan Westo.Upon arrival of the participants, they are briefed with the stages of the experiment, risks and usage of their data. The briefing is concluded with asking if they have any questions regarding the experiment, and that further briefing will be delivered after the experiment is done. The participant reads the briefing of the experiment and sign the consent form.The participant is asked to remove all metal objects from their clothing, or preferably change to a metal-free lab cloth. The body of the participants should be scanned using metal detection to assure no metal was forgotten to be taken off. Standard contraindications to MRIs should be respected.The participant is asked to enter the fMRI laboratory for a configuration of the video projector and audio system. Assure that the headphones are presenting the sound correctly. The participant lies down on an fMRI bed while a sample video is played to see if the picture is easily visible, and the audio level is comfortable and clear.Should any complaints arise from the participant, adjustments should be made accordingly. Connect the fMRI-compatible eye tracking system. The tracking is used to assure that the subject is attentive during the experiment, and does not fall asleep or daydream during the fMRI scan.Once the eye tracking is secured, start the calibration process to begin recording the eye movements. Inform the subject that the experiment is about to begin, and instruct the participants to relax as if they were to watch a TV program in his or her home. Remind the participant to follow the instruction slides that will guide them through the scan of the different steps.Now, go ahead and start the fMRI scan. Move the participant to a different room where additional behavior data can be collected. Once all the data is collected, debrief the participant of the actual aim of the experiment, and answer any additional questions that might arise.During the fMRI scan, the participant will be presented with a 30-minute audiovisual content, which includes instruction slides, four minutes baseline measurement, a 20-minute movie, four-minute post-movie subliminal measurement, and concluding slides. Note that the movie duration can be longer if needed. The four minutes of subliminal measurements, baseline and post-movie, are identical.The participant should not be informed of the nature or purpose at this stage, and should be presented with the following instruction. Soon, you will see a calibration clip. This clip is meant for calibrating the MRI scanner for your responses.The clip is only four minutes long, and will look like white noise on a TV screen. Please keep your eyes fixated at the mark in the center of the screen until notified otherwise. Following the instruction slide, a fixation cross will appear in the middle of the screen for two seconds, followed by the four-minute stimuli for the baseline subliminal measurement.The four-minute subliminal stimuli contain white noise virtually divided into 16 blocks of 15 seconds each. The 16 blocks of white noise contain two types of blocks, a rest block, followed by a condition block. To create the four-minute subliminal stimuli, start with a 15-second white noise clip.The white noise also serves as a masking stimulus for the face that is being flashed. Therefore, use a dynamic white noise clip that has big distortion and movements. Once you have the 15-second dynamic white noise clip, go ahead and create the 15-second condition block by inserting the 10 flashes of the protagonist's face in it.The subliminal flashes should be at a 40-millisecond duration, starting at the onset of the condition block inserted every 1, 500 millisecond. For an image of the protagonist's face, you can search for an image of the actor on the internet, or you can take a frame from the movie. When using the internet, make sure the actor looks similar to his appearance in the movie.Face images taken from the internet or the movie should have a neutral face expression, big, clear, and well-lit, as well as facing the camera. Adjust the image by centering it in the middle of the screen. Make sure there are no salient things in the background of the face.If so, go ahead and cut them out or mask them to create a neutral image. Finally, flip the image from color to black and white before inserting it. Once you have the rest block and the condition block ready, duplicate them to create the four-minute subliminal stimuli.By the end of the process, you should have a four minutes containing 16 blocks each of 15 seconds. Representative results. In the following section, we will share some of the strong and weak results using post-movie subliminal measurement from our recent study.Here we investigated implicit bias among 14 homosexual and 15 heterosexual subjects toward the protagonist of the movie Priest. The 20 minutes edited version tells the story of a Catholic priest in a struggle between his devotion to his faith, and his desire to be loved by another man. To analyze the differences between the homosexual and heterosexual group, we ran a two-way mixed effect ANOVA, which compares the differences in bold responses between the face after watching the movie, versus the baseline.In line with the hypothesis, the results revealed significantly larger bold signals in the homosexual versus heterosexual subjects in response to the face of the homosexual protagonist. Although the heterosexual group also showed significance in multiple regions including right amygdala, left insula, and bilateral central sulcus, the results were not strong enough to survive correction. This implies that in-group and out-group bias might differ in their strength, and therefore, it is advised to avoid using small sample groups when conducting group comparisons.This video shows you how our method can be set up in an fMRI study. The post-movie subliminal measurement can also be used with other newer imaging modalities. When using this method, it's important to choose a movie that is engaging, professionally executed, and relevant to your topic of investigation.Luckily, a quick search on the internet can help you find any movie depicting any social group in almost any language. This what makes movie characters a great candidate as a stimulus to investigate social perception and implicit bias.

post-movie-subliminal-measurement-pmsm-for-investigating-implicit

Research

JoVE Journal

Neuroscience

5.5K vistas.  Aalto University. La medición subliminal posterior a la película puede ayudar a responder preguntas clave para entender el neuroprocesamiento subyacente a la percepción social, como cómo el conocimiento contextual sesga nuestra respuesta implícita hacia los demás. El sesgo implícito es un fenómeno muy difícil de investigar. Al presentar estímulos durante períodos muy breves de tiempo, se puede medir la respuesta implícita del cerebro que percibe el procesamiento consciente.En nuestro nuevo p...