Emotive Concept-Nouns and Motor Responses: Attraction or Repulsion?

Transcription

1 Emotive Concept-Nouns and Motor Responses: Attraction or Repulsion? Laura Freina Communication Disciplines Department, Bologna University Via Azzo Gardino 23, Bologna Giulia Baroni Communication Disciplines Department, Bologna University Via Azzo Gardino 23, Bologna Anna Borghi Psychology Department, Bologna University Viale Berti Pichat 5, Bologna Roberto Nicoletti Communication Disciplines Department, Bologna University Via Azzo Gardino 23, Bologna Abstract Chen and Bargh (1999) demonstrated that participants answered more quickly to negative words by pushing a lever away than by pulling it towards themselves; the opposite was true for positive words. We designed two experiments to test the hypothesis that this effect depends on the answer modality, using the same stimuli as the original experiment. Answers had to be given using a modified keyboard with two oversized buttons. To read the words, subjects pressed the central space-bar, then they moved the hand away or towards their body to press the answer button. In Experiment 1 subjects had to classify each word as positive or negative by hitting the corresponding button with their hand open. Shorter RTs were obtained when pressing the far button for positive words and the near button for negative words, demonstrating that the different answer modality influences RTs. In Experiment 2 we hypothesized that, when participants hold something in their hand, the effect should be the opposite: shorter RTs should be obtained when participants have to perform an away-movement for negative words and a towards-movement for positive words. Results suggest that, when participants use their empty hand, they simulate a reaching movement, therefore perform better in withdrawing from negative words and grasping positive ones. The opposite may be true when they hold something in their hand: they simulate pushing it away or drawing it towards them. Results are discussed within theories on concept grounding in emotion and action systems. Embodied Cognition and Language Comprehension In the last years, the embodied cognition approach, according to which our cognitive system is grounded in sensory-motor processes, is gradually overtaking the traditional cognitive view according to which mind is a device for manipulating arbitrary symbols. The new position is emerging in all the fields related to cognitive sciences such as philosophy (Clark, 1997; Prinz, 2002), neurosciences (Berthoz, 1997, Pulvermüller, 2003; Rizzolatti and Arbib, 1998), and experimental psychology (Barsalou, 1999; Glenberg, 1997; Elsner and Hommel, 2001). In addition, many computational models based on an embodied approach have been proposed (e.g. Elman, Bates, Johnson, Karmiloff-Smith, Parisi and Plunkett, 1996; Nolfi and Floreano, 2000). According to the embodied theory, concepts consist of the reactivation of the same neural activation pattern that is present when we perceive the objects or entities they refer to and when we interact with them (Barsalou, 1999; Borghi, 2005; Gallese and Lakoff, 2005; Glenberg, 1997). The same manner, according to the embodied view, understanding language implies forming a simulation, that is the recruitment of the very neurons that would be activated when actually acting or perceiving the situation, action, object or entity described by language. (Barsalou, 1999; Gallese & Lakoff, 2005; Gibbs, 2003; Glenberg, 1997; McWhinney, 1999; Zwaan, 2004). Accordingly, the same systems recruited for action and emotion are employed in language comprehension. In this line, recent evidence shows that the motor system and the evaluation of emotional terms are strictly interwoven. For example, learning the meaning of a word while we are performing a specific movement can cause us to evaluate that word in a positive / negative manner. Cacioppo, Priester and Berntson (1993) demonstrated the effect of arm movement on the attitude people have towards Chinese ideograms they did not know. When they made an approach movement - i.e. they were required to pull the arm near their body in order to respond - they tended to provide a better evaluation of the ideograms than when the

2 movement was of repulsion - i.e. they extended their arms away from their body to respond. In a more recent study, Chen and Bargh (1999) showed participants words with a positive / negative emotive valence like love and hate. Their task was to answer to the word s emotive valence by pulling / pushing a lever near / far from their body. Reaction times (RTs) were quicker when there was congruence between arm movement and word valence (pulling near for positive words and pushing away for negative words). The same result was obtained when participants were not required to provide an evaluation but were asked only to react to words when they appeared on the computer screen. Similar results have been obtained with a task of noun generation. Participants had to write the names of famous people and then make an evaluation with a movement that could be of approach or avoidance. (Foerster and Strack, 1997). Results show that people tended to produce names of famous people they liked or disliked congruently with the movement they made. Even though the reported evidence suggests that during sentence comprehension we activate simulations and that we recruit the motor system during the evaluation of emotional terms, the extent to which these simulations are specific is still a matter of debate. In our work we sought to investigate the degree of specificity of these simulations. More specifically, we sought to understand whether reading sentences related to actions having a different meaning activates the same neural systems activated during the effective execution of these actions. Experiment 1 Open Hand Experiment (OAExp) Hypothesis Chen and Bargh (1999) found that people were quicker when they had to pull the lever towards their body for positive words and when they had to push the lever away for negative words. They claimed that this result depended on the fact that when reading a negative term, people activate their arm to make an avoidance movement i.e. to push the negative object away. The opposite is true for positive words. If the simulations we run during word comprehension are quite detailed, then we predict that the results will be influenced by the answer modality. More specifically, we predict that that when subjects do not have to move a lever, but are making a grasping movement with their hand open, the opposite results may be obtained. People should therefore be quicker in reaching the far button when reading a positive word (reaching for the object) and in taking their hand back near the body (avoiding to touch a negative object) for negative words. Method Stimuli We selected the original 92 words used by Chen and Bargh (1999; Bargh et al. 1992), translated them into Italian and then we asked 25 students of the Communication Disciplines Department to evaluate them using a questionnaire. For each word, separated evaluations of their positive and negative valence have been asked. Then two separate scores have been computed for each word: the first gives a positive / negative evaluation, the second the word s ambivalence. The score computation has been done using the same method as the Bargh et al. (1992) experiment. From the original sample, we selected 58 words choosing, among those words which have less ambivalence, the most positive and the most negative ones. Another 10 words were selected for the training session. Apparatus A modified keyboard with only the space bar and two oversized buttons was used. The answer buttons were labeled with the words POSITIVO (positive) and NEGATIVO (negative), written in a big font so that the labels could be easily read. The keyboard was placed vertically, so that one of the two answering buttons was near the subject s body while the other was far away from the body and near the computer screen. The space bar was located in the middle between the two answering buttons. The apparatus with the modified keyboard

3 The experiment took place in a dimly lit and noiseless room. Participants were seated facing a 17 cathode-ray tube screen driven by a 700 MHz computer. E-Prime 1.1 software was used. Procedure Participants were asked to classify as quickly as possible each word as positive or negative by hitting the corresponding button with their right hand. To start each trial the subject had to press the black part of the space bar, which forces the right hand in a central position. After the space bar was pressed, a cross appeared in the middle of the screen for 500 milliseconds, after which it was replaced by a word. The stimulus stayed on the screen until the subject pressed either the positive or the negative button. After each trial a feedback stating the answer time appeared on the screen. To start the following trial the space bar had to be pressed again. Results and Discussion As the error analyses revealed that there was no speed-for-accuracy tradeoff, we focused on the RT analyses. To screen for outliers, scores 2 standard deviations higher or lower than the mean participant score were removed for each participant. The remaining response times were submitted to a mixed 2x2 ANOVA with the factor Answer Modality (NNFP vs. NFPN) manipulated between participants and the factor Word Valence (Positive vs. Negative) manipulated within participants. Open Hand Experiment In the Negative Near Positive Far (NNPF) condition subjects had to press the far button for positive words and the near button for negative words (we predicted that this condition would produce quicker reaction times since it is congruent with the reaching movement for positive words and withdrawal for negative ones). The Negative Far Positive Near (NFPN) condition had the two answering buttons changed. Each subject was randomly assigned to the NNPF or the NFPN condition. The experiment was preceded by a short training session of 10 stimulus. The experimenter went out of the room during the experiment. Participants 42 students from the Communication Disciplines Department of the Bologna University took part in the experiment. Two subjects have later been discharged because they made too many classification errors (they classified more than 8 words in a different manner from average). The 40 subjects left were 17 males and 23 females, average age with a standard deviation of 2.39, ranging from 20 to 30. All had normal vision or corrected to normal. Five of them were left handed. As predicted, the NNPF condition was significantly faster than the NFPN one (F(1,38) = 5.94; Mse = ; p <.02). Participants were faster in reaching rather than withdrawing when they read a positive word and faster to withdraw rather than reach when they processed a negative word. There was no significant difference between the positive and the negative stimulus response time. The interaction between Answer Modality (NNPF vs. NFPN) and Word Valence (positive vs. negative) was also significant (F(1,38) = 17.10; Mse = ; p <.0002). Post-hoc Newman-Keuls showed that this was due to the fact that the negative-near condition was the quickest while the negative-far one was the slowest (p <.0005). The OAExp demonstrates that the answer modality influences reaction times. In the Chen and Bargh (1999) experiment, people were quicker in extending their arm when faced with a negative term, since arm extension is considered a movement of avoidance. In our experiment the opposite results are obtained: people are quicker in withdrawing their open hand from the negative object.

4 Experiment 2 Tennis Ball Experiment (TBExp) Hypothesis Supposing that the results of the OAExp were due to the empty open hand condition, we designed the TBExp in which participants were asked to hold a tennis ball in their hand while answering. We assumed that, since subjects have something in their hand, they could no more associate the pressing of the far button with a reaching movement, but rather with the pushing away of something. The near answer would then be associated with pulling something towards one s body. Under these conditions, we expected to obtain the same results as Chen and Bargh (1999), even though their interpretation focused on arm movement rather than hand position. Method The TBExp uses exactly the same apparatus, procedure and stimuli as the OAExp. The only difference is that subjects are asked to answer by hitting the buttons while holding a tennis ball in their right hand. Tennis Ball Experiment Participants 47 students from the Communication Disciplines Department of the Bologna University took part in the experiment. None of them had taken part to the OAExp. Seven subjects were later discarded because they made too many classification errors (they classified more than 8 words in a different manner from average). The 40 subjects left were 18 males and 22 females, average age with a standard deviation of 2.33, ranging from 19 to 29. All had normal vision or corrected to normal. One participant was left handed. Results and Discussion As the error analyses revealed that there was no speed-for-accuracy tradeoff, we focused on the RT analyses. To screen for outliers, scores 2 standard deviations higher or lower than the mean participant score were removed for each participant. The remaining response times were submitted to a mixed 2x2 ANOVA with the factor Answer Modality (NNFP vs. NFPN) manipulated between participants and the factor Word Valence (Positive / Negative) manipulated within participants. We obtained a significant difference between the positive and the negative Word Valence (F(1,38) = 9.56; Mse = ; p <.0037), but the factor Answer Modality did not reach significance. There was a significant interaction between Answer Modality and Word Valence (NNPF vs. NFPN conditions and positive vs. negative stimuli) (F(1,38) = 14.90; Mse = ; p <.0004). Post-hoc Newman-Keuls showed that, while negative RTs were almost the same for both Answer Modalities (NNPF vs. NFPN), the positive-near condition resulted to be faster than all the other (p <.0002). The TBExp aimed at a further investigation on the answer modality influence on reaction times. As predicted, we found faster RTs when participants had to pull an object in their hand towards their body while processing positive words. Results were not as predicted for negative stimuli, as we did not find faster RTs when people had to push away from their body the object in their hand while processing a negative word. Comparison OAExp TBExp We run a mixed ANOVA on response times with the factors Experiment (OAExp vs. TBExp) and Answer Modality (NNFP vs. NFPN) manipulated between participants and the factor Word Valence (Positive vs. Negative) manipulated within participants. Interestingly, we found a significant interaction between Experiment and Answer Modality (OAExp vs. TBExp and NNPF vs. NFPN conditions) (F(1,76) = 4.41; Mse = ; p <.039) and a significant difference between the

5 positive and the negative stimuli (F(1,76) = 9.54; Mse = ; p <.0028). We also got a significant interaction between Answer Modality (NNPF vs. NFPN) and Word Valence (Positive / Negative) (F(1,76)=32.01; MSe= ; p< ). The post-hoc test Newman-Keuls test shows that the NFPN-negative RTs were slower than all the other RTs, while other differences were not significant. General discussion Our study clearly shows that the influence of emotive concept word evaluation on movement depends on the answer modality. As predicted, our study suggest that the simulation run during word comprehension and evaluation is quite detailed, as it is sensitive to the answer modality. In Experiment 1 (OAExp) we demonstrated that the influence of emotive concept word evaluation on movement depends on the answer modality. Chen and Bargh (1999) found quicker RTs when participants had to push a lever away from their body while we had faster RTs when participants had to withdraw with their open hand from a negative concept word. The opposite was true for positive words. In our experiment, participants had to answer with their empty hand open, and we found faster RTs when they had to withdraw from a negative concept (moving their hand away from the computer screen and near their body) and when they had to make a grasping movement while processing a positive concept (moving the hand near the computer screen). In Experiment 2 (TBExp) we changed the answer modality. Participants had to hold a tennis ball in their hand while pressing the answer buttons, simulating the movement of pulling near / pushing away something that they held in their hand. According to our hypothesis, participants should have been faster in the NFPN condition (i.e. when they had to push away a negative concept and pull near a positive one). For positive concept we actually found that RTs were quicker when participants had to draw their hand towards their body while holding a tennis ball, and slower RTs when they had to push the ball away. For negative words we did not find significant differences in RTs. One possible explanation for this is that the act of hitting the far button (near the computer screen and far from the participant body) could be associated not to the throwing away of a held object but rather to the act of hitting the negative object with the ball. So when a participant reads the word SPIDER, he/she could react quickly and try to kill the awful animal with the ball. Further analysis is needed to try to distinguish between those words which can be hit with a tennis ball held in the hand (like SPIDER ) and those that cannot be treated in such a way (like MONDAY ). Acknowledgments Many thanks to Valentina Bazzarin, Claudia Gianelli, Luisa Lugli, Antonello Pellicano, Claudia Scorolli, Annalisa Setti and Alessia Tessari for all their useful comments. A special thanks to Antonello Pellicano for letting us use the modified keyboard. References Bargh, J.A., Chaiken, S., Govender, R. & Pratto F. (1992). The Generality of the Automatic Activation Effect. Journal of Personality and Social Psychology, 62 (6), Barsalou, L.W. (1999). Perceptual symbol systems. Behavioral and Brain Sciences, 22, Berthoz, A. (1997). Le sens du mouvement. Paris: Odile Jacob. Borghi, A. & Nicoletti, R. (in press). Se leggo capello mi muovo verso l alto: movimento e comprensione di parole e frasi. Giornale

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