Pre-attentive processing is the subconscious accumulation of information from the environment.Atienza, M., Cantero, J. L., & Escera, C. (2001). Auditory information processing during human sleep as revealed by event-related brain potentials. Clinical Neurophysiology, 112(11), 2031-2045.Van der Heijden, A. H. C. (1996). Perception for selection, selection for action, and action for perception. Visual Cognition, 3(4), 357-361. All available information is pre-attentively processed. Then, the brain filters and processes what is important. Information that has the highest salience (a stimulus that stands out the most) or relevance to what a person is thinking about is selected for further and more complete analysis by conscious (attentive) processing. Understanding how pre-attentive processing works is useful in advertising, in education, and for prediction of cognitive ability.
Pure-capture and contingent-capture
The reasons are unclear as to why certain information proceeds from pre-attentive to attentive processing while other information does not. It is generally accepted that the selection involves an interaction between the salience of a stimulus and person's current intentions and/or goals.Egeth, H. E., Yantis, S. (1997). Visual attention: Control, representation, and time course. Annual Review of Psychology, 48, 269-297. Two models of pre-attentive processing are pure-capture and contingent-capture.Folk, C. L., & Remington, R. (2006). Top-down modulation of preattentive processing: Testing the recovery account of contingent capture. Visual Cognition, 14, 445-465.
The "pure-capture" model focuses on stimulus salience.Tollner, T., Zehetleitner, M., Gramann, K., & Muller, H. J. (2010). Top-down weighting of visual dimensions: Behavioral and electrophysiological evidence. Vision Research, 50(14), 1372-1381. If certain properties of a stimulus stand out from its background, the stimulus has a higher chance of being selected for attentive processing. This is sometimes referred to as "bottom-up" processing, as it is the properties of the stimuli which affect selection. Since things that affect pre-attentive processing do not necessarily correlate with things that affect attention, stimulus salience may be more important than conscious goals. For example, pre-attentive processing is slowed by sleep deprivation while attention, although less focused, is not slowed.Raz, A., Deouell, L. Y., & Bentin, S. (2001). Is pre-attentive processing compromised by prolonged wakefulness? Effects of total sleep deprivation on the mismatch negativity. Psychophysiology, 38, 787-795. Furthermore, when searching for a particular visual stimulus among a variety of visual distractions, people often have more trouble finding what they are looking for if one or more of the distractions is particularly salient. For example, it is easier to locate a bright, green circle (which is salient) among distractor circles if they are all grey (a bland color) than it is to locate a green circle among distractor circles if some are red (also salient colour). This is thought to occur because the salient red circles attract our attention away from the target green circle. However, this is difficult to prove because when given a target (like the green circle) to search for in a laboratory experiment, participants may generalize the task to searching for anything that stands out, rather than solely searching for the target. If this happens, the conscious goal becomes finding anything that stands out, which would direct the person's attention towards red distractor circles as well as the green target. This means that a person's goal, rather than the salience of the stimuli, could be causing the delayed ability to find the target.
The "contingent-capture" model emphasizes the idea that a person's current intentions and/or goals affect the speed and efficiency of pre-attentive processing. The brain directs an individual's attention towards stimuli with features that fit in with their goals. Consequently, these stimuli will be processed faster at the pre-attentive stage and will be more likely to be selected for attentive processing. Since this model focuses on the importance of conscious processes (rather than properties of the stimulus itself) in selecting information for attentive processing, it is sometimes called "top-down" selection. In support of this model, it has been shown that a target stimulus can be located faster if it is preceded by the presentation of a similar, priming stimulus. For example, if an individual is shown the color green and then required to find a green circle among distractors, the initial exposure to the color will make it easier to find the green circle. This is because they are already thinking about and envisioning the color green, so when it shows up again as the green circle, their brain readily directs its attention towards it. This suggests that processing an initial stimulus speeds up a person's ability to select a similar target from pre-attentive processing. However, it could be that the speed of pre-attentive processing itself is not affected by the first stimulus, but rather that people are simply able to quickly abandon dissimilar stimuli, enabling them to re-engage to the correct target more quickly. This would mean that the difference in reaction time occurs at the attentive level, after pre-attentive processing and stimulus selection has already taken place.
Vision Information for pre-attentive processing is detected through the senses. In the visual system, the receptive fields at the back of the eye (retina) transfer the image via axons to the thalamus, specifically the lateral geniculate nuclei.Meng, X., & Wang, Z. (2009). A pre-attentive model of biological vision. IEEE International Conference on Intelligent Computing and Intelligent Systems, 3, 154-158. The image then travels to the primary visual cortex and continues on to be processed by the visual association cortex. At each stage, the image is processed with increasing complexity. Pre-attentive processing starts with the retinal image; this image is magnified as it moves from retina to the cortex of the brain. Shades of light and dark are processed in the lateral geniculate nuclei of the thalamus. Simple and complex cells in the brain process boundary and surface information by deciphering the image's contrast, orientation, and edges. When the image hits the fovea, it is highly magnified, facilitating object recognition. The images in the periphery are less clear but help to create a complete image used for scene perception.Klein, S. A., Carney, T., Barghout-Stein, L., & Tyler, C. W. (1997, June). Seven models of masking. In Electronic Imaging'97 (pp. 13-24). International Society for Optics and Photonics.Barghout-Stein, Lauren. On differences between peripheral and foveal pattern masking. Diss. University of California, Berkeley, 1999.
Visual scene segmentation is a pre-attentive process where stimuli are grouped together into specific objects against a background.Appelbaum, L. G., & Norcia, A. M. (2009). Attentive and pre-attentive aspects of figural processing. Journal of Vision, 9(11), 1-12. Figure and background regions of an image activate different processing centres: figures use the lateral occipital areas (which involve object processing) and background engages dorso-medial areas.Kourtzi, Z., & Kanwisher, N. (2000). Cortical regions involved in perceiving object shape. Journal of Neuroscience, 20, 3310-3318.
Visual pre-attentive processing uses a distinct memory mechanism.Krummenacher, J., Grubert, A., & Müller, H. J. (2010). Inter-trial and redundant-signals effects in visual search and discrimination tasks: Separable pre-attentive and post-selective effects. Vision Research, 50(14), 1382-1395. When a stimulus is presented consecutively, the stimulus is perceived at a faster rate than if different stimuli are presented consecutively. The theory behind this is called the dimension-weighting account (DWA) where each time a specific stimulus (i.e. color) is presented it contributes to the weight of the stimuli. More presentations increase the weight of the stimuli, and therefore, subsequently decrease the reaction time to the stimulus. The dimensional-weighting system, which calculates pre-attentive processing for our visual system, codes the stimulus and thus directs attention to the stimulus with the most weight.
Visual pre-attentive processing is also involved in the perception of emotion.Balconi, M., & Mazza, G. (2009). Consciousness and emotion: ERP modulation and attentive vs. pre-attentive elaboration of emotional facial expressions by backward masking. Springer Science, 33, 113-124. Human beings are social creatures and are very adept at critiquing facial expressions. We have the ability to unconsciously process emotional stimuli and equate the stimuli, such as a face, with meaning.
Audition The auditory system is also very important in accumulating information for pre-attentive processing. When a person's eardrum is struck by incoming sound waves, it vibrates. This sends messages, via the auditory nerve, to the brain for pre-attentive processing. The ability to adequately filter information from pre-attentive processing to attentive processing is necessary for the normal development of social skills.Seri, S., Pisani, F., Thai, J. N., & Cerquiglini, A. (2007). Pre-attentive auditory sensory processing in autistic spectrum disorder. Are electromagnetic measurements telling us a coherent story? International Journal of Psychophysiology, 63(2), 159-163. For acoustic pre-attentive processing, the temporal cortex was believed to be the main site of activation; however, recent evidence has indicated involvement of the frontal cortex as well.Habermeyer, B., Herdener, M., Esposito, F., Hilti, C. C., Klarhofer, M., di Salle, F., Wetzel, S., et al. (2009). Neural correlates of pre-attentive processing of pattern deviance in professional musicians. Human Brain Mapping, 30, 3736-3747.Klamer, D., Svensson, L., Fejgin, K., & Palson, E. (2011). Prefrontal NMDA receptor antagonism reduces impairments in pre-attentive information processing. European Neuropsychopharmacology, 21(3), 248-253. The frontal cortex is predominantly associated with attentional processing, but it may also be involved in pre-attentive processing of complex or salient acoustic stimuli. For example, detecting slight variations in complex musical patterns has been shown to activate the right ventromedial prefrontal cortex.
It has been shown that in acoustic pre-attentive processing there is some degree of lateralization.Zaehle, T., Jancke, L., Herrmann, C. S., Meyer, M. (2009). Pre-attentive spectro-temporal feature processing in the human auditory system. Brain Topography, 22, 97-108. The left hemisphere responds more to temporal acoustic information whereas the right hemisphere responds to the frequency of auditory information. Also, there is lateralization in the perception of speech which is left hemisphere dominant for pre-attentive processing.Sorokin, A., Alku, P., & Kujala, T. (2010). Change and novelty detection in speech and non-speech sound streams. Brain Research, 1327, 77-90. .
Multisensory integration