05 08 2012 I Midterm 2 A Tuesday May 15 B Review Session 1 Friday May 11 2 30 4pm 2 Franz 1178 C Chapters 4 5 in the book as well as lectures on that material II Instrumental Behavior A Behavior that occurs because it was previously instrumental in producing a certain consequence B Appears to be goal directed 1 Is actually goal directed in some cases 2 Might be habitual rather than goal directed C Response outcome contingency 1 We learn new behaviors through a trial and error process 2 Law of effect describes how the consequences of a behavior and increase or decrease the future probability of that behavior a The outcome of response has an effect on learning b If the stimulus is followed by a satisfying event the association between the stimulus and the response is strengthened and vice versa c The strength of the S R association determines the probability of the response in the presence of the stimulus D Thorndike s cat puzzle box experiments E Discrete Trial Procedures W S Small 1 To study learning in rats 2 Put the subject in one area let them make a response then pick the rat up and put it back in the start chamber each trial is discrete 3 Straight alley maze a Measure running speed or latency to reach the goal i If time to reach the goal decreases running speed must be increasing b T maze involves a choice or direction i Consequences of the decision will influence future decisions If food is always placed on the left or if there are different types of food on each side F Operant Instrumental Conditioning 1 Skinner developed a free operant procedure and the Skinner Box a Free operant procedures allow the animal to repeat the instrumental response without constraint the rat can keep pressing the button and keep getting food b Shaping i Magazine training food is delivered here ii Attending to the lever iii Touching the lever iv Pressing the lever c Measure response rate 2 Two important factors a Response reinforcer contingency i Positive response causes the reinforce to be delivered ii Negative response prevents a reinforce from being delivered b Valence of outcome i Appetitive something we like ii Aversive something we don t like c Positive reinforcement d Negative reinforcement i Escape response taking action to prevent a bad situation that you re in ii Avoidance taking action to prevent a bad outcome that you anticipate iii Omission to decrease an instrumental response by creating a negative contingency between the response and appetitive outcome Differential Reinforcement of Other behavior DRO e Response outcome contingency table in the lecture slides III Elements of Instrumental Conditioning A Instrumental response 1 Behavioral Variability vs stereotypy a Initial variability in behavior is critical like natural selection acting on phenotypes b Behavior generally becomes less variable over time c Creativity can be reinforced as well 2 Page Neuringer 1985 a Pigeons reinforced for pecking 2 response keys 8 times in a row b Variability group is reinforced for pecking in novel patterns c Control group is reinforced for any sequence of pecking i Link individuals from the variability and control groups to keep their reinforcement schedule equal and control for various factors d The data show that the individuals in the variability group do increase variability over several trials the control group individuals do not their variability decreases i Behavior becomes more stereotyped over time ii We don t know why the variability goes down in this particular experiment B Reinforcer