Unconscious manipulation of free choice in humans

Previous research has shown that subliminally presented stimuli accelerate or delay responses afforded by supraliminally presented stimuli. Our experiments extend these findings by showing that unconscious stimuli even affect free choices between responses. Thus, actions that are phenomenally experienced as freely chosen are influenced without the actor becoming aware of the manipulation. However, the unconscious influence is limited to a response bias, as participants chose the primed response only in up to 60% of the trials. LRP data in free choice trials indicate that the prime was not ineffective in trials in which participants chose the non-primed response as then it delayed performance of the incongruently primed response.

[1]  S. Geisser,et al.  On methods in the analysis of profile data , 1959 .

[2]  Scott E. Maxwell,et al.  A Monte Carlo Comparison of Seven ε-Adjustment Procedures in Repeated Measures Designs With Small Sample Sizes , 1994 .

[3]  E. Reingold,et al.  Theory and measurement in the study of unconscious processes , 1990 .

[4]  Martin Eimer,et al.  Masked prime stimuli can bias “free” choices between response alternatives , 2004, Psychonomic bulletin & review.

[5]  G. Humphreys,et al.  Consciousness: Psychological and Philosophical Essays , 1993 .

[6]  M. Eimer,et al.  Effects of masked stimuli on motor activation: behavioral and electrophysiological evidence. , 1998, Journal of experimental psychology. Human perception and performance.

[7]  J T Mordkoff,et al.  Detecting the onset of the lateralized readiness potential: a comparison of available methods and procedures. , 2000, Psychophysiology.

[8]  S. Dehaene,et al.  Imaging unconscious semantic priming , 1998, Nature.

[9]  Wilfried Kunde,et al.  Sequential modulations of stimulus-response correspondence effects depend on awareness of response conflict , 2003, Psychonomic bulletin & review.

[10]  S. Klapp,et al.  The negative compatibility effect: Unconscious inhibition influences reaction time and response selection , 2002 .

[11]  H. Jasper.  Report of the committee on methods of clinical examination in electroencephalography , 1958 .

[12]  D. Shanks,et al.  Characteristics of dissociable human learning systems , 1994, Behavioral and Brain Sciences.

[13]  Daniel Holender,et al.  Semantic activation without conscious identification in dichotic listening, parafoveal vision, and visual masking: A survey and appraisal , 1986, Behavioral and Brain Sciences.

[14]  Rolf Verleger,et al.  Qualitative differences between conscious and nonconscious processing? On inverse priming induced by masked arrows. , 2004, Journal of experimental psychology. General.

[15]  Brian W. Haas,et al.  Nonconscious influence of masked stimuli on response selection is limited to concrete stimulus-response associations. , 2005, Journal of experimental psychology. Human perception and performance.

[16]  Martin Eimer,et al.  The lateralized readiness potential as an on-line measure of central response activation processes , 1998 .

[17]  J. Schwarzbach,et al.  Different time courses for visual perception and action priming , 2003, Proceedings of the National Academy of Sciences of the United States of America.

[18]  M. Coles.  Modern mind-brain reading: psychophysiology, physiology, and cognition. , 1989, Psychophysiology.

[19]  S. Maxwell,et al.  A Monte Carlo Comparison of Seven ε-Adjustment Procedures in Repeated Measures Designs with Small Sample Sizes@@@A Monte Carlo Comparison of Seven e-Adjustment Procedures in Repeated Measures Designs with Small Sample Sizes , 1994 .

[20]  G. Aschersleben,et al.  Intention-based and stimulus-based mechanisms in action selection , 2005, Experimental Brain Research.

[21]  E Donchin,et al.  A new method for off-line removal of ocular artifact. , 1983, Electroencephalography and clinical neurophysiology.

[22]  M. Damian.  Congruity effects evoked by subliminally presented primes: automaticity rather than semantic processing. , 2001 .

[23]  Richard L. Abrams,et al.  Three Cognitive Markers of Unconscious Semantic Activation , 1996, Science.

[24]  Peter E. Keller,et al.  Differences Between Intention-Based and Stimulus-Based Actions , 2006 .

[25]  J. Hoffmann,et al.  Conscious control over the content of unconscious cognition , 2003, Cognition.

[26]  Martin Eimer,et al.  Motor activation with and without inhibition: Evidence for a threshold mechanism in motor control , 2002, Perception & psychophysics.

[27]  H. Huynh,et al.  Estimation of the Box Correction for Degrees of Freedom from Sample Data in Randomized Block and Split-Plot Designs , 1976 .

[28]  M. Moscovitch,et al.  Attention and Performance 15: Conscious and Nonconscious Information Processing , 1994 .

[29]  Jonathan Grainger,et al.  Unconscious semantic priming from pictures , 1999, Cognition.

[30]  J. Enns,et al.  Negative compatibility or object updating? A cautionary tale of mask-dependent priming. , 2004, Journal of experimental psychology. General.

[31]  O. Neumann,et al.  Motor activation without conscious discrimination in metacontrast masking. , 1999 .