ELECTROPHYSIOLOGICAL CORRELATES OF MULTIPLE OBJECT PROCESSING PhD student: Silvia Pagano Advisor: Veronica Mazza Doctoral School in Cognitive and Brain Sciences XXV Cycle Center for Mind/Brain Sciences (CIMeC), University of Trento 1 2 Table of contents Abstract ............................................................................................................................ 7 Chapter 1 ......................................................................................................................... 9 1.1 Experimental paradigms for the study of multiple object processing .............. 11 1.1.1 Reviewing paradigm ....................................................................................... 11 1.1.2 Multiple object tracking ................................................................................. 14 1.1.3 Enumeration tasks ......................................................................................... 16 1.2 Theories of multiple object processing ................................................................. 20 1.2.1 The FINSTs theory ......................................................................................... 21 1.2.2 The object-file theory ..................................................................................... 25 1.2.3 The neural object-file theory .......................................................................... 27 1.3 Electrophysiological correlates of multiple object processing ........................... 29 1.3.1 N2pc ............................................................................................................... 29 1.3.2 CDA ................................................................................................................ 32 1.4 Rationale of the present thesis .............................................................................. 34 Chapter 2 ....................................................................................................................... 37 2.1 Experiment 1........................................................................................................... 37 2.1.1 Methods .......................................................................................................... 43 2.1.1.1 Participants ................................................................................................. 43 2.1.1.2 Stimuli and procedure ................................................................................. 43 2.1.1.3 EEG recording and data analysis ............................................................... 44 2.1.2 Results ............................................................................................................ 47 2.1.2.1 Behavioral results ....................................................................................... 47 2.1.2.1.1 RTs ........................................................................................................... 47 2.1.2.1.2 Accuracy ............................................................................................... 48 2.1.2.2 ERP results ................................................................................................. 49 2.1.2.2.1 N1 ......................................................................................................... 49 2.1.2.2.2 P2p ....................................................................................................... 50 2.1.2.2.3 N2pc ..................................................................................................... 51 2.1.2.2.4 CDA ...................................................................................................... 51 2.1.2.3 Group analysis ............................................................................................ 51 2.1.2.4 Correlational analyses ................................................................................ 54 2.1.3 Discussion ....................................................................................................... 56 2.2 Experiment 2........................................................................................................... 58 2.2.1 Participants ..................................................................................................... 59 2.2.2 Stimuli and procedure ..................................................................................... 59 3 2.2.3 EEG recordings and analysis .......................................................................... 60 2.2.4 Results ............................................................................................................ 61 2.2.5 Discussion ....................................................................................................... 63 2.3 General Discussion ................................................................................................. 64 Chapter 3 ....................................................................................................................... 71 3.1 Experiment 3........................................................................................................... 71 3.2 General Methods ............................................................................................... 77 3.2.1 Participants .................................................................................................... 77 3.2.2 Stimuli and procedure .................................................................................... 77 3.2.3 EEG recording and data analysis .................................................................. 78 3.3 Results ............................................................................................................... 80 3.3.1 Behavioral results .......................................................................................... 80 3.3.2 ERP results .................................................................................................... 81 3.3.2.1 N1 ............................................................................................................ 81 3.3.2.2 N2pc ........................................................................................................ 83 3.2.2.3 Control analysis ...................................................................................... 85 3.3 Discussion .......................................................................................................... 85 Chapter 4 ....................................................................................................................... 91 4.1 Experiment 4........................................................................................................... 91 4.2 Methods ............................................................................................................. 94 4.2.1 Participants .................................................................................................... 94 4.2.2 Stimuli and procedure .................................................................................... 94 4.2.3 EEG recordings and data analysis ................................................................ 96 4.3 Results ............................................................................................................... 97 4.4 Discussion .......................................................................................................... 99 Chapter 5 ..................................................................................................................... 101 5.1 Experiment 5a: Masking shapes ......................................................................... 106 5.1.2 Participants ................................................................................................... 107 5.1.3 Stimuli and Procedure .................................................................................. 107 5.1.4 Results and discussion .................................................................................. 108 5.2 Experiment 5b: Masking colors .......................................................................... 109 5.2.1 Participants ................................................................................................... 109 5.2.2 Stimuli and Procedure .................................................................................. 110 5.2.3 Results and discussion .................................................................................. 110 5.3 Experiment 5c: The final paradigm ................................................................... 111 5.3.1 Participants ................................................................................................... 112 5.3.2 Stimuli and Procedure .................................................................................. 112 5.3.3 Results and discussion .................................................................................. 113 4 5.4 Experiment 6: Electrophysiological correlates of multiple object processing in the absence of awareness ....................................................................................... 114 5.4.1 Participants ................................................................................................... 114 5.4.2 Stimuli and procedure ................................................................................... 114 5.4.4 EEG recordings and analysis ........................................................................ 115 5.4.5 Results 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