Neurological role of context in affective/non-affective primacy Asmita Bhattacharya, Y8148 SE367 Report The Ad hoc Cognition model advocates the contention that all concepts, categorizations and semantics are constructed ad hoc in our minds, whenever we use them, from basic raw structures already stored in the brain. This involves the integration of the affective (emotional) evaluation and non-affective (semantic) evaluation of any situation that is presented to us. The authors on whose work this project is based puts forward the idea that the relative speed with which affective/non-affective processing occurs in response to stimuli is context-dependent, and is not decided according to any fixed paradigm. This project aims to establish a neurological support for this Ad hoc Cognition model. The first part of this project is the duplication of the authors’ experiment and results to establish context’s role in processing. The next part involves imaging the brains of subjects by functional magnetic resonance imaging (fMRI) as the same experiment is conducted. Introduction : When people see a spider, their brains process both non-affective information (a spider is an animal) and affective information (the spider is dangerous). Affective information refers to the emotional aspect and non-affective side refers to the semantic aspect of any phenomenon. The question as to which of these two processing occur first has been rampant for several years now. The Affective Primacy Hypothesis (affective evaluation is quicker and automatic) and the Cognitive Primacy Hypothesis (people need to understand what they are seeing before they can feel anything about it) have attributed temporal primacy to affective and non-affective processing respectively. The paper under discussion here proposes that the relative speed with which affective/non-affective processing occurs in response to stimuli is context-dependent. As a small example, they have pointed out that, for a person hiking in a tropical jungle, the affective information gets priority as he is constantly reminded of the possibly dangerous animals lurking around him. However, for a person classifying animals as part of a timed biology test, the non affective details (various physical features of animals) are far more important than if some of them are dangerous or not. In my project, I wish to establish a neurological support for the model proposed by the authors of this paper. I wish to conduct similar experiments as described in the paper, while imaging the brains of the subject by functional magnetic resonance imaging - fMRI, thus showing effective neurological signification of context being the determinant of the processing pathway for the affective and non- affective aspects of stimuli. Previous Work : Earlier experiments using fMRI data has shown that when exposed to emotional stimuli, a neural system is activated that learns the affective value of the stimuli. The explanation given was that this system is present to provide for a shortcut that by-passes the neural system responsible for identification of objects and people and is capable of producing a fast reaction to stimuli that are potentially life-threatening. However, past experiments have generally always focused on the affective processing of emotionally loaded words being shown to subjects. Variations had been done with the degree of valence (unpleasant/pleasant) and arousal (intensity of emotion) of the presented stimuli. This was mapped to distinct parts of the brain for assessing valence and arousal respectively, by rating the stimuli. fMRI data showed that various ratings correlated with various areas in the brain (around the amygdala). However, the authors of the aforesaid paper subscribe to the school of thought advocating “Ad Hoc Cognition: context dependent processing”. The authors have leaned towards the proposition that perhaps all categorizations, concepts and semantics are constructed ad hoc, whenever we use them. And the details of this construction are determined by the manner in which retrieval cues relate to the physical, linguistic and social context they are in. A pair of direct examples of such a system comes from the fact that the emotional tone of words heard can determine the nature of subsequent processing of the words, and that studies have shown that affective processing is often goal-dependent or task-relevant. If concepts, categories, and word meanings are stable, how can people use them so flexibly? Here we explore a possible answer: maybe this stability is an illusion. – Casasanto, D. & Lupyan, G. (2011). Ad Hoc Cognition Experiments done by the authors of this paper are aimed at participants processing the same stimuli in different contexts. In order to provide for contexts, they took inspiration from Allport and Wylie (2000) Task Set Inertia paradigm which proposes that that readiness for a given task (i.e. task set) involuntarily tends to persist over a number of successive trials, kind of like a high-order of priming. Here the authors have used target trials (stimuli such as words of affective/non-affective dimension) and filler trials (stimuli such as scenes of affective/non-affective dimension). The theory is that evaluation during the filler trials will persist and influence evaluation during the target trials. So, the filler trials are serving as a context that can orient the test-taker towards a certain aspect of the target trial stimuli. As result of the experiments done by these authors, it had seemed that processing (hence reaction time) of any information in the brain works according to cues-in-context available at the time. Thus any broad generalizations regarding the temporal primacy of a particular kind of evaluation seems baseless. The authors of this paper rather support the framework of Ad Hoc Cognition which advocates that words and scenes stimulate a unique neuro-cognitive processing every time they are encountered. And the context in which the stimuli are present plays a very important role in determining the details of such a processing. Hypothesis : The authors of the earlier paper rather support the framework of Ad Hoc Cognition which advocates that the context in which the stimuli are present plays a very important role in determining the details of processing affective and non-affective aspects of a stimulus. This experiment could show that with affective context, the affective processing centres of the brain show higher/primal activity, whereas with non-affective context, the non-affective processing centres of the brain show higher/primal activity. Materials And Methods : • Two modes for the target and filler trials were selected – written words and pictures, as stimuli items. • 
A group of people were asked to rate the valence (positive/negative) and the arousal (intensity of emotion) components of a large number of stimuli selected. After that, only the stimuli of similar arousal levels were selected and grouped into filler trials (for context) and target trials (for response). • 8 subjects were selected from among English speakers such that they have no history of neurological problems, and are of similar age group (IITK undergraduates). • As per the assumptions of Task-Set-Inertia paradigm, each subject was subjected to alternating filler trials and target trials one by one. This was done in 2 groups for each of the 2 modalities: affective context group and non-affective context group. • Targets for Expt1 (Fillers for Expt2): 32 words of 4 categories: positive human (princess), negative human (murderer), positive animal (rabbit), negative animal (cockroach). Fillers for Expt1 (Targets for Expt2): 32 pictures of 4 categories: pleasant outdoor, pleasant indoor, unpleasant outdoor, unpleasant indoor. • Each subject judged (according to following instructions) each stimulus presented for 0.5 seconds: Expt1 Affective context: Filler picture: “Unpleasant”/“Pleasant”; Target word: “Positive”/“Negative”/“Animal”/“Human”. Expt1 Non-affective context: Filler picture: “Indoor”/“Outdoor”; Target word: “Positive”/“Negative”/“Animal”/“Human”. Expt2 Affective context: Filler word: “Positive”/“Negative”; Target picture: “Unpleasant”/“Pleasant”/“Indoor”/“Outdoor” Expt2 Non-affective context: Filler word: “Animal”/“Human”; Target picture: “Unpleasant”/“Pleasant”/“Indoor”/“Outdoor”. • The reaction time (RT) for verbal affective/non-affective judgment was recorded for the targets, and graphs were plotted, as shown in the next section. • Expt2 is a repetition of Expt1, only with the modalities of target filler trials exchanged. • On 27 th November 2011, this pair of experiments is to be repeated at the fMRI centre of SGPGI hospital, Lucknow. As the judgment is being made, the brain of the subject will be imaged by fMRI, with amygdala being the focus for affective processing centre, and the hippocampus for non- affective processing centre. The details of these brain areas are to be decided after consulting a psychologist once the scans are available. • The scans obtained are to be analyzed qualitatively with appropriate software to find agreement with our hypothesis. Results And Discussion : • In Expt1, as predicted, with affective contexts, affective judgments were made faster (less RT) than non-affective ones; and with non-affective contexts, non-affective judgments were made faster (less RT) than affective ones. • In Expt2, as predicted, with affective contexts, affective judgments were made faster (less RT) than non-affective ones; however, with non-affective contexts, non-affective judgments were made faster (less RT) than affective ones. • The biasing towards affective judgment, predicted by authors of the paper while using picture stimuli (because of affective load carried by the detailed colored photos), was not found in this experiment. A possible explanation could be the less sharp nature of the images used, as well as the much less number of subjects used in these tests. • The overall idea of the authors’ experiments was successfully reproduced in these experiments. However, error bars and average RT were much larger in my data than in their work, probably because of poorer measurement techniques. My own reaction time in using the stopwatch is also a confounding factor here, since reaction times around the average of ~0.70 seconds was to be measured. • Other major differences in results obtained could be because of the facts that the number of subjects used by me was only 8 whereas the authors had used around 40 subjects, and also that the sample set for target stimuli had 32 items in my data, whereas the authors had used 96 items. • The final step involves repeating the experiment using the same target-filler set up while getting fMRI images of 4 subjects’ brains on 27 th November at SGPGI, Lucknow. The scan time is to be synchronized with the time lapse between the stimuli (i.e. effective RT). Full brain imaging is to be done, as areas to focus on are not clear. Preferably, response to stimuli is to be a motor signal, and not speech, as speech entails greater processing (noise). Also, occipital cortex noise is to be excluded from further analysis. References : 1. Murphy, S.T. & Zajonc, R.B. Affect, cognition, and awareness: affective priming with optimal and suboptimal stimulus exposures. J Pers Soc Psychol 64, 723-739 (1993). 2. Calvo, M.G. &Nummenmaa, L. Processing of unattended emotional visual scenes. J Exp Psychol Gen 136, 347-369 (2007). 3. Whalen, P.J., et al. Masked presentations of emotional facial expressions modulate amygdala activity without explicit knowledge. J Neurosci 18, 411-418 (1998). 4. Storbeck, J.& Robinson, M .D. Preferences and inferences in encoding visual objects: a systematic comparison of semantic and affective priming. Pers Soc Psychol Bull 30, 81-93 (2004). 5. Nummenmaa, L., Hyona, J. & Calvo, M.G. Semantic categorization precedes affective evaluation of visual scenes. J Exp Psychol Gen 139, 222-246. 6. Elman, J.L. An alternative view of the mental lexicon. Trends Cogn Sci 8, 301-306 (2004). 7. Vicky Tzuyin Lai, Peter Hagoort, Daniel Casasanto. Affective and Non-affective Meaning in Words and Pictures. Cognitive Sciences Society. Annual Conference 2011.
