MATLAB for Psychologists

Description

1 Basic Operations ..................................................................................... 1 Variables .................................................................................................... 5 Thinking in a Matrix Way ......................................................................... 8 Operations ................................................................................................. 15 Summary ................................................................................................... 17 Exercises ................................................................................................... 18 A Brick for an Experiment ........................................................................ 20 References ................................................................................................. 23 Suggested Readings .................................................................................. 23 2 Data Handling ......................................................................................... 25 Types of Variables (Logical Values, Strings, NaN, Structures, Cells) ...... 25 Logical Variables................................................................................... 25 Strings ................................................................................................... 31 NaN ....................................................................................................... 35 Structures .............................................................................................. 35 Cells ...................................................................................................... 38 Import/Export ............................................................................................ 40 Summary ................................................................................................... 42 Exercises ................................................................................................... 43 A Brick for an Experiment ........................................................................ 44 Read the Results .................................................................................... 44 Reference .................................................................................................. 46 Suggested Readings .................................................................................. 46 3 Plotting Data ............................................................................................ 47 Plot Data .................................................................................................... 47 Control the Plot’s Objects: Labels, Legend, Title… ................................. 50 Subplot: Multiple Plots in One Figure ...................................................... 52 3-D Plots ................................................................................................... 56 Printing and Saving Images ...................................................................... 58 Contents xii Contents Handle Graphics ........................................................................................ 58 Summary ................................................................................................... 61 Exercises ................................................................................................... 62 A Brick for an Experiment ........................................................................ 64 Plot the Results ..................................................................................... 64 Reference .................................................................................................. 65 Suggested Readings .................................................................................. 65 4 Start Programming ................................................................................. 67 M-Scripts and Functions ........................................................................... 67 Control Flow Statements........................................................................... 70 Cycles and Conditionals: If ................................................................... 70 Switch Case ........................................................................................... 72 For Loops ............................................................................................. 74 While .................................................................................................... 78 Break ..................................................................................................... 81 Try–Catch ............................................................................................. 82 Loops Versus Matrices and If Versus Logicals ..................................... 82 Functions ................................................................................................... 83 Scope of Variables ................................................................................. 86 Change the Number of Inputs and Outputs ........................................... 87 More on Data Import/Export: Script Examples ........................................ 90 Analysis ................................................................................................ 95 Guidelines for a Good Programming Style ............................................... 96 Writing Code ......................................................................................... 96 Debug .................................................................................................... 98 Summary ................................................................................................... 100 Exercises ................................................................................................... 101 A Brick for an Experiment ........................................................................ 102 Analysis ................................................................................................ 104 References ................................................................................................. 106 Suggested Readings .................................................................................. 106 5 A Better Sound ......................................................................................... 107 Generate a Sound ...................................................................................... 107 Multiple Sounds ........................................................................................ 112 Manipulating a Sound’s Level .................................................................. 114 Match the Level of Sound with Different Waveforms .......................... 115 Stereophonic Sounds for ITD and ILD ..................................................... 116 A Sound’s Envelope .................................................................................. 118 Sound Filtering.......................................................................................... 120 Sound Analysis.......................................................................................... 123 Summary ................................................................................................... 125 Exercises ................................................................................................... 125 Contents xiii A Brick for an Experiment ........................................................................ 126 References ................................................................................................. 127 Suggested Readings .................................................................................. 128 6 Create and Proccess Images ................................................................... 129 Images Basics ............................................................................................ 129 Importing and Exporting Images .......................................................... 132 Display Images ...................................................................................... 134 Basic Manipulation of Images .................................................................. 135 Point Operations ........................................................................................ 136 Intensity Transformation ....................................................................... 136 Windowing ............................................................................................ 138 Neighborhood Processing ......................................................................... 140 The Edges of the Image ........................................................................ 144 Advanced Image Processing ..................................................................... 144 Creating Images by Computation ............................................................. 144 Summary ................................................................................................... 149 Exercises ................................................................................................... 150 References ................................................................................................. 151 Suggested Readings .................................................................................. 152 7 Data Analysis ........................................................................................... 153 Descriptive Statistics ................................................................................. 153 Measures of Central Tendency .............................................................. 153 Measures of Dispersion ......................................................................... 154 Bivariate and Multivariate Descriptive Statistics ..................................... 155 Covariance ............................................................................................ 156 Simple and Multiple Linear Regression ............................................... 156 Generalized Linear Model .................................................................... 160 Inferential Statistics .................................................................................. 162 Parametric Statistics .............................................................................. 162 t-Test ..................................................................................................... 163 ANOVA ................................................................................................. 166 Nonparametric Statistics ........................................................................... 177 Categorical Data .................................................................................... 177 Ordinal Data .......................................................................................... 179 Signal-Detection Theory (STD) Indexes .............................................. 182 Summary ................................................................................................... 184 Exercises ................................................................................................... 185 A Brick for an Experiment ........................................................................ 186 References ................................................................................................. 187 Suggested Readings .................................................................................. 187 xiv Contents 8 The Charm of Graphical User Interface ............................................... 189 Introduction ............................................................................................... 189 GUIDE ...................................................................................................... 189 Starting GUIDE .................................................................................... 190 The GUI Toolbar ....................................................................................... 190 Adding UiControls to the GUI .............................................................. 191 Closing the GUI .................................................................................... 193 Controlling UiControls from Other UiControls ........................................ 196 The Sum-Two-Numbers Example ........................................................ 196 Displaying Graphs and Figures in the GUI ........................................... 202 Saving User Input ..................................................................................... 204 Adding Your Own Functions ................................................................ 207 A Brick for an Experiment ........................................................................ 212 Appendix ................................................................................................... 215 The File Menu ....................................................................................... 216 The Edit Menu ...................................................................................... 216 The View Menu ..................................................................................... 217 The Layout Menu .................................................................................. 217 Tools Menu ........................................................................................... 218 Help ....................................................................................................... 218 Preferences for GUIDE ............................................................................. 219 Backward Compatibility ....................................................................... 220 Other Preferences .................................................................................. 221 Suggested Readings .................................................................................. 221 9 Psychtoolbox: Video ................................................................................ 223 The Screen Function ................................................................................. 223 Analysis ................................................................................................ 225 How to Use Screen to Get Information ..................................................... 225 How to Use Screen to Draw Figures ......................................................... 227 Preliminary Notions: Drawing Figures in Three Steps—Opening, Drawing, and Closing ........................................................................... 227 Opening the Window ............................................................................ 227 Drawing: An Introduction ..................................................................... 229 Closing .................................................................................................. 230 Drawing: Reprise ...................................................................................... 230 Analysis ................................................................................................ 231 Drawing Shapes .................................................................................... 231 Batch Processing: Drawing Multiple Figures at Once .............................. 235 Drawing Text ............................................................................................. 236 Importing Images ...................................................................................... 238 Analysis ................................................................................................. 239 Video Clips ................................................................................................ 240 Analysis ................................................................................................. 240 Analysis ................................................................................................. 241 Drawing Things at the Right Time ............................................................ 241 Contents xv Analysis ................................................................................................. 243 Summary ................................................................................................... 243 Exercises ................................................................................................... 244 Exercise 1 .............................................................................................. 244 Solution 1 .............................................................................................. 244 Exercise 2 .............................................................................................. 244 Solution 2 .............................................................................................. 245 A Brick for an Experiment ........................................................................ 245 References ................................................................................................. 248 Suggested Readings .................................................................................. 248 10 Psychtoolbox: Sound, Keyboard and Mouse ........................................ 249 Timing ....................................................................................................... 249 Priority ...................................................................................................... 250 Sound Functions........................................................................................ 251 Getting Participants’ Inputs: Keyboard and Mouse Functions ................. 253 Keyboard Response .............................................................................. 253 “Press Any Key to Proceed” ................................................................. 254 “Press the Spacebar to Proceed” ........................................................... 254 “Press Any Key to Respond” ................................................................ 256 Reaction-Time Detection ...................................................................... 256 Choice Reaction Time ........................................................................... 258 Go/No-Go Reaction Time ..................................................................... 259 Reaction Times Within a Video Clip..................................................... 260 Mouse Input .......................................................................................... 262 Using Participants’ Input to Manipulate Shape Characteristics ................ 263 Keyboard Manipulations ....................................................................... 264 Placing Discs with the Mouse ............................................................... 266 Summary ................................................................................................... 267 Exercises ................................................................................................... 268 Exercise 1 ............................................................................................. 268 A Brick for an Experiment ........................................................................ 269 References ................................................................................................. 272 Suggested Readings .................................................................................. 273 About the Authors ........................................................................................... 275 Index ................................................................................................................ 277