MATLAB for Psychologists [recurso electrónico

The matrix laboratory interactive computing environment—MATLAB—has brought creativity to research in diverse disciplines, particularly in designing and programming experiments. More commonly used in mathematics and the sciences, it also lends itself to a variety of applications across the field of psychology. For the novice looking to use it in experimental psychology research, though, becoming familiar with MATLAB can be a daunting task. __MATLAB for Psychologists__ expertly guides readers through the component steps, skills, and operations of the software, with plentiful graphics and examples to match the reader’s comfort level. Using an extended illustration, this concise volume explains the program’s usefulness at any point in an experiment, without the limits imposed by other types of software. And the authors demonstrate the responsiveness of MATLAB to the individual’s research needs, whether the task is programming experiments, creating sensory stimuli, running simulations, or calculating statistics for data analysis. Key features of the coverage: * Thinking in a matrix way. * Handling and plotting data. Guidelines for improved programming, sound, and imaging.* Statistical analysis and signal detection theory indexes. * The Graphical User Interface. * The Psychophysics Toolbox. __MATLAB for Psychologists__ serves a wide audience of advanced undergraduate and graduate level psychology students, professors, and researchers as well as lab technicians involved in programming psychology experiments. 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