The Choice Blindness Lab

Choice Blindness Lab: Lars Hall, Petter Johansson, Andreas Lind, Philip Pärnamets, Thomas Strandberg

We’re a research lab at Lund University Cognitive Science that studies questions concerning the role of external feedback for cognitive processes ranging from preferences and attitudes to emotion and speech production. The lab uses a variety of experimental methods, including magical self-transforming surveys, real-time speech exchange, and gaze-contingent manipulation of decision times. The primary tool of the lab, from which it also gathers its name, is the Choice Blindness paradigm.

Choice Blindness

Choice Blindness is a research paradigm originally inspired by techniques from the domain of close-up card-magic, which permits us to manipulate the relationship between what people choose, and what they actually get. We have investigated choice blindness in domains such as aesthetic-, moral-, political- and consumer choice, and in the modalities of vision, voice, taste and smell, and we have consistently found that participants often fail to notice mismatches between what they choose and what they get. In addition, we have found that participants often confabulate arguments why they actually prefer the alternative they had initially rejected. You can read more about choice blindness here.

Current research in the lab

Choice blindness and preference change. We are interested in the effects receiving false feedback about one’s choices affects future preferences. We have shown that individuals’ will change their preference, in light of their beliefs about their past choices (Johansson et al., 2014). Ongoing projects in the lab are investigating these effects with more than one participant (dyads choosing together), as well as, the effects of choice blindness manipulations on individuals’ memories of their past preferences.

Choice blindness and political attitudes. We have shown that peoples’ political and moral attitudes are susceptible to manipulations using self-transforming magical surveys (Hall, Johansson & Strandberg, 2012; Hall et al., 2013). Ongoing projects include conducting large scale surveys of political attitudes and meta-attitudes allowing us to probe political attitudes and different measures of attitude strength correlate and how false feedback about one’s attitude might affect one’s related meta-attitudes.

Choice blindness and implicit measures. To better understand what happens when participants accept false feedback about their choices ongoing projects are using a number of measures other than self-report to study choice blindness, including eye-movements, pupil dilation and mouse-arm movements.

Real time speech exchange. We have developed a novel method which allows us to study how auditory feedback is used by speakers to help specify the meaning of what they themselves are saying, and how feedback interacts with the sense of agency during language production (Lind et al., 2014). We are currently investigating the role of feedback for the self-attribution of emotions.

Gaze and moral choice. We have developed a novel method whereby we terminate participant’s deliberation on the basis of their viewing patterns, allowing us to influence peoples’ responses to difficult moral questions (Pärnamets et al., 2015). Ongoing projects investigate how moral decisions are formed in the moment using eye-movements and computational models.


[2016-01-13] New publication!

Abstract of method and findings.

Research has shown that people often exert control over their emotions. By modulating expressions, reappraising feelings, and redirecting attention, they can regulate their emotional experience. These findings have contributed to a blurring of the traditional boundaries between cognitive and emotional processes, and it has been suggested that emotional signals are produced in a goal-directed way and monitored for errors like other intentional actions. However, this interesting possibility has never been experimentally tested. To this end, we created a digital audio platform to covertly modify the emotional tone of participants’ voices while they talked in the direction of happiness, sadness, or fear. The result showed that the audio transformations were being perceived as natural examples of the intended emotions, but the great majority of the participants, nevertheless, remained unaware that their own voices were being manipulated. This finding indicates that people are not continuously monitoring their own voice to make sure that it meets a predetermined emotional target. Instead, as a consequence of listening to their altered voices, the emotional state of the participants changed in congruence with the emotion portrayed, which was measured by both self-report and skin conductance level. This change is the first evidence, to our knowledge, of peripheral feedback effects on emotional experience in the auditory domain. As such, our result reinforces the wider framework of self-perception theory: that we often use the same inferential strategies to understand ourselves as those that we use to understand others.

[2015-03-16] New publication!
The same decision trajectory can be biased towards a randomly selected=

Abstract of method and findings.

Eye gaze is a window onto cognitive processing in tasks such as spatial memory, linguistic processing, and decision making. We present evidence that information derived from eye gaze can be used to change the course of individuals’ decisions, even when they are reasoning about high-level, moral issues. Previous studies have shown that when an experimenter actively controls what an individual sees the experimenter can affect simple decisions with alternatives of almost equal valence. Here we show that if an experimenter passively knows when individuals move their eyes the experimenter can change complex moral decisions. This causal effect is achieved by simply adjusting the timing of the decisions. We monitored participants’ eye movements during a two-alternative forced-choice task with moral questions. One option was randomly predetermined as a target. At the moment participants had fixated the target option for a set amount of time we terminated their deliberation and prompted them to choose between the two alternatives. Although participants were unaware of this gaze-contingent manipulation, their choices were systematically biased toward the target option. We conclude that even abstract moral cognition is partly constituted by interactions with the immediate environment and is likely supported by gaze-dependent decision processes. By tracking the interplay between individuals, their sensorimotor systems, and the environment, we can influence the outcome of a decision without directly manipulating the content of the information available to them.

[2014-04-29] New publication!

Speech is usually assumed to start with a clearly defined preverbal message, which provides a benchmark for self-monitoring and a robust sense of agency for one’s utterances. However, an alternative hypothesis states that speakers often have no detailed preview of what they are about to say, and that they instead use auditory feedback to infer the meaning of their words. In the experiment reported here, participants performed a Stroop color-naming task while we covertly manipulated their auditory feedback in real time so that they said one thing but heard themselves saying something else. Under ideal timing conditions, two thirds of these semantic exchanges went undetected by the participants, and in 85% of all non-detected exchanges, the inserted words were experienced as self-produced. These findings indicate that the sense of agency for speech has a strong inferential component, and that auditory feedback of one’s own voice acts as a pathway for semantic monitoring, potentially overriding other feedback loops.

[2014-04-29] New publication!



What would it be like if we said one thing, and heard ourselves saying something else? Would we notice something was wrong? Or would we believe we said the thing we heard? Is feedback of our own speech only used to detect errors, or does it also help to specify the meaning of what we say? Comparator models of self-monitoring favor the first alternative, and hold that our sense of agency is given by the comparison between intentions and outcomes, while inferential models argue that agency is a more fluent construct, dependent on contextual inferences about the most likely cause of an action. In this paper, we present a theory about the use of feedback during speech. Specifically, we discuss inferential models of speech production that question the standard comparator assumption that the meaning of our utterances is fully specified before articulation. We then argue that auditory feedback provides speakers with a channel for high-level, semantic “self-comprehension”. In support of this we discuss results using a method we recently developed called Real-time Speech Exchange (RSE). In our first study using RSE (Lind et al., 2014) participants were fitted with headsets and performed a computerized Stroop task. We surreptitiously recorded words they said, and later in the test we played them back at the exact same time that the participants uttered something else, while blocking the actual feedback of their voice. Thus, participants said one thing, but heard themselves saying something else. The results showed that when timing conditions were ideal, more than two thirds of the manipulations went undetected. Crucially, in a large proportion of the non-detected manipulated trials, the inserted words were experienced as self-produced by the participants. This indicates that our sense of agency for speech has a strong inferential component, and that auditory feedback of our own voice acts as a pathway for semantic monitoring. We believe RSE holds great promise as a tool for investigating the role of auditory feedback during speech, and we suggest a number of future studies to serve this purpose.

[2014-03-17] New publication!



The current study is the first to investigate confabulatory introspection in relation to clinical psychological symptoms utilizing the Choice Blindness Paradigm (CBP). It was hypothesized that those with obsessive-compulsive symptoms are more like- ly to confabulate mental states. To test this hypothesis, an experimental choice blindness task was administered in two nonclinical samples (n = 47; n = 76). Re- sults showed that a confabulatory introspection is significantly related to obsessive- compulsive symptoms. There was evidence for its specificity to symptoms of OCD depending on the obsessional theme addressed in the choice blindness task. How- ever, confabulatory introspection was also found to be relevant to other symptoms, including depression and schizotypy. The results highlight a potentially fruitful new area of clinical investigation in the area of insight and self-knowledge, not limited to OCD alone, but potentially other disorders as well.

[2013-10-23] New publication!



Choice blindness is the finding that participants both often fail to notice mismatches between their decisions and the outcome of their choice and, in addition, endorse the opposite of their chosen alternative. But do these preference reversals also carry over to future choices and ratings? To investigate this question, we gave participants the task of choosing which of a pair of faces they found most attractive. Unknown to them, we sometimes used a card trick to exchange one face for the other. Both decision theory and common sense strongly suggest that most people would easily notice such a radical change in the outcome of a choice. But that was not the case: no more than a third of the exchanges were detected by the participants. We also included a second round of choices using the same face pairs, and two stages of post‐choice attractiveness ratings of the faces. This way we were able to measure preference strength both as choice consistency and by looking at measures of rating differences between chosen and rejected options. We found that the initially rejected faces were chosen more frequently in the second choice, and the perceived attractiveness of these faces was increased even in uncoupled individual ratings at the end of the experiment. This result is discussed in relation to Chen and Risen’s recent criticism of the Free Choice Paradigm, as it shows that choices can affect future preferences.

[2013-04-10] New publication!

Political candidates often believe they must focus their campaign efforts on a small number of swing voters open for ideological change. Based on the wisdom of opinion polls, this might seem like a good idea. But do most voters really hold their political attitudes so firmly that they are unreceptive to persuasion? We tested this premise during the most recent general election in Sweden, in which a left- and a right-wing coalition were locked in a close race. We asked our participants to state their voter intention, and presented them with a political survey of wedge issues between the two coalitions. Using a sleight-of-hand we then altered their replies to place them in the opposite political camp, and invited them to reason about their attitudes on the manipulated issues. Finally, we summarized their survey score, and asked for their voter intention again. The results showed that no more than 22% of the manipulated replies were detected, and that a full 92% of the participants accepted and endorsed our altered political survey score. Furthermore, the final voter intention question indicated that as many as 48% were willing to consider a left-right coalition shift. This can be contrasted with the established polls tracking the Swedish election, which registered maximally 10% voters open for a swing. Our results indicate that political attitudes and partisan divisions can be far more flexible than what is assumed by the polls, and that people can reason about the factual issues of the campaign with considerable openness to change.

[2012-09-19] New publication!



What exactly are opinions? What does it mean to express an attitude? Given the ubiquitous use of surveys, polls and rating scales, it seems we ought to have firm answers to these fundamental questions, but we do not. Here we present a novel approach to investigate the nature of attitudes. We created a self-transforming paper survey of moral opinions, covering both foundational principles, and current dilemmas hotly debated in the media. This survey ‘magically’ exposed participants to a reversal of their previously stated attitudes, allowing us to record whether they were prepared to endorse and argue for the opposite view of what they had stated only moments ago. The result showed that the majority of the reversals remained undetected, and a full 69% of the participants failed to detect at least one of two changes. In addition, participants often constructed coherent and unequivocal arguments supporting the opposite of their original position. These results suggest a dramatic potential for flexibility in our moral attitudes, and indicates a clear role for self-attribution and post-hoc rationalization in attitude formation and change.




Aucouturier, J.J., Johansson, P., Hall, L., Segnini, R., Mercadiéf, L., & Watanabe, K. (2016). Covert digital manipulation of vocal emotion alter speakers’ emotional states in a congruent direction. Proceedings of the National Academy of Sciences. doi: 10.1073/pnas.1506552113 . [Open Access Link]


Lind, A., Hall, L., Breidegard, B., Balkenius, C., & Johansson, P. (2015). Auditory Feedback Is Used for Self-Comprehension: When We Hear Ourselves Saying Something Other Than What We Said, We Believe We Said What We Hear. Psychological Science. doi:10.1177/0956797615599341 [PDF]

Trouche, E., Johansson, P., Hall, L., & Mercier, H. (2015). The Selective Laziness of Reasoning. Cognitive Science. [PDF]

Cheung, T., Junghans, A. F., Dijksterhuis, G. B., Kroese, F., Johansson, P., Hall, L., & De Ridder, D. T. D. (2015). Consumers’ Choice-Blindness to Ingredient Information. Appetite. [PDF]

Pärnamets, P., Johansson, R., Gidlöf, K., & Wallin, A. (2015). How Information Availability Interacts with Visual Attention during Judgment and Decision Tasks. Journal of Behavioral Decision Making. 10.1002/bdm.1902 [PDF]

Pärnamets, P., Hall, L., & Johansson, P. (2015). Memory distortions resulting from a choice blindness task. In D. C. Noelle, R. Dale, A. S. Warlaumont, J. Yoshimi, T. Matlock, C.D. Jennings, & P. P. Maglio (Eds.), Proceedings of the 37th Annual Conference of the Cognitive Science Society (pp. 1823-1828). Austin, TX : Cognitive Science Society. [PDF]

Pärnamets, P. (2015). A fixation dependent model of charitable choice. Lund University Cognitive Studies. 161. [PDF]

Pärnamets, P. (2015). Observing and manipulating preferences in real time. Lund University Cognitive Studies. 160. PhD Thesis. [PDF]

Pärnamets, P., Johansson, P., Hall, L., Balkenius, C., Spivey, M.J., & Richardson, D.C. (2015). Biasing moral decisions by exploiting the dynamics of eye gaze. Proceedings of the National Academy of Sciences. doi: 10.1073/pnas.1415250112. [Open Access Link]


Lind, A., Hall, L., Breidegard, B., Balkenius, C., & Johansson, P. (2014). Speakers’ acceptance of real-time speech exchange indicates that we use auditory feedback to specify the meaning of what we say. Psychological Science. DOI: 10.1177/0956797614529797 [PDF]

Lind, A., Hall, L., Breidegard, B., Balkenius, C., & Johansson, P. (2014). Auditory feedback of one’s own voice is used for high-level, semantic monitoring: The “self- comprehension” hypothesis. Frontiers in Human Neuroscience, 8, Article 166. DOI: 10.3389/fnhum.2014.00166 [PDF]

Pärnamets, P., Balkenius, C. & Richardson, D. C. (2014). Modelling moral choice as a diffusion process dependent on visual fixations. In Bello, P., Guarini, M., McShane, M. & Scassellati, B. (eds.) Proceedings of the 36th Annual Conference of the Cognitive Science Society. Cognitive Science Society, Austin, TX. [PDF]

Aardema, F, Johansson, P, Hall, L, Paradisis, S-M, Zidani, M and Roberts, S (2014) Choice Blindness, Confabulatory Introspection, and Obsessive-Compulsion Symptoms: A New Era of Investigation. International Journal of Cognitive Therapy, 7(1), 83-102 [PDF]


Johansson, P., Hall, L., Tärning, B., Sikström, S., & Chater, N. (2013). Choice Blindness and Preference Change: You Will Like This Paper Better If You (Believe You) Chose to Read It! Journal of Behavioral Decision Making. DOI:10.1002/bdm.1807. [PDF]

Hall, L., Strandberg, T., Pärnamets, P., Lind, A., Tärning, B. and Johansson, P. (2013). How the Polls Can Be Both Spot On and Dead Wrong: Using Choice Blindness to Shift Political Attitudes and Voter Intentions. PLoS ONE 8(4): e60554. doi:10.1371/journal.pone.0060554. [Link]

Hall, L., Johansson, P., & de Léon, D. (2013). Recomposing the Will: Distributed motivation and computer mediated extrospection. In T. Vierkant, A. Clark & J. Kiverstein (Eds.) (2013). Decomposing the will. Oxford University Press: Philosophy of Mind Series. pp. 298-324. [PDF]


Hall, L., Johansson, P., & Strandberg, T. (2012). Lifting the veil of morality: choice blindness and attitude reversals on a self-transforming survey. PloS one, 7(9), e45457. doi:10.1371/journal.pone.0045457 [PDF]


Chater, N., Johansson, P., & Hall, L. (2011). The non-existence of risk attitude. Frontiers in psychology, 2, 303. doi:10.3389/fpsyg.2011.00303 [PDF]

Johansson, P., Hall, L., & Gärdenfors, P. (2011). Choice blindness and the nonunitary nature of the human mind. Behavioral and Brain Sciences, 34(1), 28- 29.

Johansson, L., Hall, L., & Chater, N. (2011). Preference change through choice. In R. Dolan & T. Sharot (Eds.) (2011). Neuroscience of Preference and Choice. Elsevier Academic Press. pp. 121-141. [PDF]

– 2010

Hall, L., Johansson, P., Tärning, B., Sikström, S.,&Deutgen, T. (2010). Magic at the marketplace: Choice blindness for the taste of jam and the smell of tea. Cognition, 117(1), 54–61. doi:10.1016/j.cognition.2010.06.010 [PDF]

Hall, L & Johansson, P. (2009). Choice Blindness: You don’t know what you want. New Scientist, Issue 2704, 26‐27. [PDF]

Johansson, Hall & Sikström 2008 – From Change Blindness to Choice Blindness. Psychologia, 51, 142-155. [PDF]

Johansson, P., Hall, L., Gulz, A., Haake, M., & Watanabe, K. (2007). Choice blindness and trust in the virtual world. Technical report of Institute of Electronics, Information and Communication Engineers – Human Information Proceessing (IEICE-HIP), 107(60), 83-86. [PDF]

Johansson, P., Hall, L., Sikström, S., Tärning, B. & Lind, A. (2006). How something can be said about Telling More Than We Can Know. Consciousness and Cognition, 15, 673-692 [PDF].

Johansson, P., Hall, L., Sikström, S., & Olsson, A. (2005). Failure to detect mismatches between intention and outcome in a simple decision task. Science (New York, N.Y.), 310(5745), 116–9. doi:10.1126/science.1111709. [PDF]

Choice Blindness on YoutubeChoice Blindness on Youtube



Biasing moral decisions study covered in Nature News, Science Daily, and Huffington Post. Interviews with Philip Pärnamets on Swedish TV4 Nyhetsmorgon and with Daniel Richardson on BBC5 ‘Naked Scientist’ radio show and for Dutch radio.

Find out more about our Lifting the Veil of Morality study in Nature News, LiveScience, and Science Daily.

Faces & Jam in BBC Horizon

Why did I do that? in Reader’s Digest

At the heart of attraction lies confusion, in PsyBlog

Radio interview with Petter Johansson, in The Sound of Science

Radio interview with Petter Johansson and the Magician Tom Stone, in SR P1 Filosofiska rummet.

The Choice Blindness Lab is jointly led by Lars Hall and Petter Johansson. If you would like to know more about current directions of research at the lab or are interested in collaborating with us, please contact Petter Johansson ( or Lars Hall (