Individuation of multiple targets during visual enumeration: New insights from electrophysiology

Visual enumeration of small numerosities critically depends on the capacity of our visual system to process multiple objects as distinct entities. We assessed the functioning of this mechanism-individuation-during computation of quantities in cluttered scenes by using ERP measures. Participants saw a variable number of targets (1, 3, 5, 7) presented among distracters, and reported their quantities. Results showed that the N2pc amplitude was modulated by target numerosity and reached a plateau at five elements, in line with the supposed limit of the individuation mechanism. In addition, the N2pc asymptote varied depending on participants' enumeration efficiency, being smaller in participants with poor enumeration performance. The results indicate that computation of small quantities is based on multiple object individuation and suggest that individual neural differences during simultaneous individuation are strongly associated with enumeration performance.

[1]  Y. Benjamini,et al.  Controlling the false discovery rate: a practical and powerful approach to multiple testing , 1995 .

[2]  P. Jolicoeur,et al.  Fundamental properties of the N2pc as an index of spatial attention: effects of masking. , 2006, Canadian journal of experimental psychology = Revue canadienne de psychologie experimentale.

[3]  Patrick Cavanagh,et al.  Attention Mechanisms for Counting in Stabilized and in Dynamic Displays , 2011 .

[4]  P. Cavanagh,et al.  Independent Resources for Attentional Tracking in the Left and Right Visual Hemifields , 2005, Psychological science.

[5]  Z. Pylyshyn,et al.  Cueing and counting: Does the position of the attentional focus affect enumeration? , 1994 .

[6]  Benoit Brisson,et al.  Dissociation of the N2pc and sustained posterior contralateral negativity in a choice response task , 2008, Brain Research.

[7]  Patrice D. Tremoulet,et al.  Indexing and the object concept: developing `what' and `where' systems , 1998, Trends in Cognitive Sciences.

[8]  Christian N. L. Olivers,et al.  Subitizing requires attention , 2008 .

[9]  E. Vogel,et al.  Neural Measures of Individual Differences in Selecting and Tracking Multiple Moving Objects , 2008, The Journal of Neuroscience.

[10]  Daniel C. Hyde,et al.  All Numbers Are Not Equal: An Electrophysiological Investigation of Small and Large Number Representations , 2009, Journal of Cognitive Neuroscience.

[11]  Z. Pylyshyn.  Visual indexes, preconceptual objects, and situated vision , 2001, Cognition.

[12]  David C Burr,et al.  Subitizing but not estimation of numerosity requires attentional resources. , 2010, Journal of vision.

[13]  Z. Pylyshyn.  The role of location indexes in spatial perception: A sketch of the FINST spatial-index model , 1989, Cognition.

[14]  N. Cowan.  The magical number 4 in short-term memory: A reconsideration of mental storage capacity , 2001, Behavioral and Brain Sciences.

[15]  M. Chun,et al.  Selecting and perceiving multiple visual objects , 2009, Trends in Cognitive Sciences.

[16]  G. Alvarez,et al.  How many locations can be selected at once? , 2007, Journal of experimental psychology. Human perception and performance.

[17]  S. Luck,et al.  Bridging the Gap between Monkey Neurophysiology and Human Perception: An Ambiguity Resolution Theory of Visual Selective Attention , 1997, Cognitive Psychology.

[18]  David C Burr,et al.  Temporal auditory capture does not affect the time course of saccadic mislocalization of visual stimuli. , 2010, Journal of vision.

[19]  Alfonso Caramazza,et al.  Attention selection, distractor suppression and N2pc , 2009, Cortex.

[20]  N. P. Bichot,et al.  Visual selection mediated by location: Feature-based selection of noncontiguous locations , 1999, Perception & psychophysics.

[21]  G. Mandler,et al.  Subitizing: an analysis of its component processes. , 1982, Journal of experimental psychology. General.

[22]  Alfonso Caramazza,et al.  Temporal Brain Dynamics of Multiple Object Processing: The Flexibility of Individuation , 2011, PloS one.

[23]  G. Woodman,et al.  Dissociations Among Attention, Perception, and Awareness During Object-Substitution Masking , 2003, Psychological science.

[24]  R. Melara,et al.  Attentional selection of objects or features: Evidence from a modified search task , 1999, Perception & psychophysics.

[25]  Nicolas Robitaille,et al.  On the control of visual spatial attention: evidence from human electrophysiology , 2006, Psychological research.

[26]  Valéria Csépe,et al.  Similarities and differences in the coding of numerical and alphabetical order using acoustic stimulation as revealed by event-related potentials in humans , 2004, Neuroscience Letters.

[27]  Z. Pylyshyn,et al.  What enumeration studies can show us about spatial attention: evidence for limited capacity preattentive processing. , 1993, Journal of experimental psychology. Human perception and performance.

[28]  Melissa E. Libertus,et al.  Electrophysiological evidence for notation independence in numerical processing , 2007, Behavioral and Brain Functions.

[29]  Bahador Bahrami,et al.  Modulating Attentional Load Affects Numerosity Estimation: Evidence against a Pre-Attentive Subitizing Mechanism , 2008, PloS one.

[30]  Lana M Trick,et al.  More than superstition: Differential effects of featural heterogeneity and change on subitizing and counting , 2008, Perception & psychophysics.

[31]  M. Eimer.  The N2pc component as an indicator of attentional selectivity. , 1996, Electroencephalography and clinical neurophysiology.

[32]  E. Vogel,et al.  Contralateral delay activity provides a neural measure of the number of representations in visual working memory. , 2010, Journal of neurophysiology.

[33]  Martin Eimer,et al.  The N2pc component and its links to attention shifts and spatially selective visual processing. , 2008, Psychophysiology.

[34]  D. Melcher,et al.  Subitizing reflects visuo-spatial object individuation capacity , 2011, Cognition.

[35]  Carlo Umiltà,et al.  Attentional selection and identification of visual objects are reflected by distinct electrophysiological responses , 2007, Experimental Brain Research.

[36]  Daniel C. Hyde,et al.  Spatial Attention Determines the Nature of Nonverbal Number Representation , 2011, Journal of Cognitive Neuroscience.

[37]  Manuela Piazza,et al.  How Humans Count: Numerosity and the Parietal Cortex , 2009, The Neuroscientist : a review journal bringing neurobiology, neurology and psychiatry.

[38]  D. Kahneman,et al.  The reviewing of object files: Object-specific integration of information , 1992, Cognitive Psychology.

[39]  Elizabeth S Spelke,et al.  Spatiotemporal dynamics of processing nonsymbolic number: An event‐related potential source localization study , 2012, Human brain mapping.

[40]  Maro G. Machizawa,et al.  Neural activity predicts individual differences in visual working memory capacity , 2004, Nature.

[41]  S. Carey,et al.  On the limits of infants' quantification of small object arrays , 2005, Cognition.

[42]  Rochel Gelman,et al.  Variability signatures distinguish verbal from nonverbal counting for both large and small numbers , 2001, Psychonomic bulletin & review.

[43]  C. Gallistel,et al.  Nonverbal Counting in Humans: The Psychophysics of Number Representation , 1999 .

[44]  Z. Pylyshyn,et al.  Why are small and large numbers enumerated differently? A limited-capacity preattentive stage in vision. , 1994, Psychological review.

[45]  Jason T. Arita,et al.  A cuing study of the N2pc component: An index of attentional deployment to objects rather than spatial locations , 2009, Brain Research.

[46]  Thaddeus B. Czuba,et al.  Motion processing with two eyes in three dimensions. , 2011, Journal of vision.

[47]  Joseph Krummenacher,et al.  Redundancy gains in pop-out visual search are determined by top-down task set: behavioral and electrophysiological evidence. , 2011, Journal of vision.

[48]  Stanislas Dehaene,et al.  The Organization of Brain Activations in Number Comparison: Event-Related Potentials and the Additive-Factors Method , 1996, Journal of Cognitive Neuroscience.

[49]  M. Posner,et al.  Brain mechanisms of quantity are similar in 5-year-old children and adults. , 1998, Proceedings of the National Academy of Sciences of the United States of America.

[50]  Susan Carey,et al.  Infants' knowledge of objects: beyond object files and object tracking , 2001, Cognition.

[51]  S. Luck,et al.  Electrophysiological correlates of feature analysis during visual search. , 1994, Psychophysiology.

[52]  Matthew M. Doran,et al.  The role of visual attention in multiple object tracking: Evidence from ERPs , 2010, Attention, perception & psychophysics.

[53]  Thomas R. Knösche,et al.  Counting in everyday life: Discrimination and enumeration , 2006, Neuropsychologia.

[54]  Harry Haroutioun Haladjian,et al.  Evidence for a shared mechanism used in multiple-object tracking and subitizing , 2011, Attention, perception & psychophysics.