Transcript LT2Ch3a
Experimental Evidence Rats drink little saccharin water at first but increase over time. Loud tones (110 db) produce different responses depending on the background noise (60 vs 80 db). Habituation occurred at 60 db Sensitization occurred at 80 db A loud background is arousing, leading to greater reactivity, not less. Conditions Producing Change More intense (stronger) stimuli produce stronger sensitization, less likely to produce habituation. Greater sensitization and habituation occur when the stimulus is repeated frequently. Changes in the stimulus prevent habituation. Turkeys respond to shape changes. Conditions (Cont.) Sensitization can occur to many kinds of stimuli but habituation occurs only with innate responses. Habituation and sensitization are transient (go away after seconds or minutes between stimuli). Except long-term habituation. Dishabituation – response returns when a sensitizing stimulus occurs. Opponent-Process Theory An explanation for addictions. All experiences produce an affective reaction (pleasant or unpleasant) – called the A state. This reaction gives rise to its opposite – called the B state. B state is less intense and lasts longer. Over time, the A state diminishes and the B state increases. The Addiction Process Tolerance – diminished A state. Withdrawal – increased B state. Addictive behavior is a coping response to the change in B state. People try to enhance A state to offset the unpleasantness of the B state. Without withdrawal symptoms there is no addictive behavior. Time prevents B state strengthening. What Sustains Addiction? The B state is a non-specific aversive feeling. Anything similarly aversive will motivate the addictive behavior, even if it has no relation to the substance. Daily life stress produces a B state that results in behavior to create an A state. Parachute jumpers – create a B state in order to feel the A state. PSY402 Theories of Learning Chapter 3 Political Classical Conditioning Examples of Conditioning Popcorn at the movies. Fear of flying -- stronger with more turbulence (a stronger UCS). An antelope shying away from low tree branches. Nausea at the smell of alcohol after a hangover. Conditioned Emotional Responses Fear is an anticipatory pain response based on past experience. Fear is conditioned whenever a CS is associated with an aversive (painful or negative) event. Fear motivates two responses: Escape (when pain is present) Avoidance (when pain is imminent) Conditioning Situations Sign-tracking (autoshaping) – animals must recognize signs of food (UCS) and respond (UCR). Pigeons pecking at key. UCR, not an operant response, because behavior is specific to the stimulus. Eyeblink conditioning UCR is rapid, CR is slow. Many trials are needed (100 pairings) Fear conditioning Avoidance is not a good measure of fear. Suppression of an operant behavior occurs with a feared stimulus. First – an operant behavior is learned. Second – a CS is paired with an aversive UCS. Third – the CS is presented in the operant chamber. Suppression Ratio During CS SuppressionRatio = During CS + Without CS The amount of time during and without the CS is equal. The more fear, the lower the suppression ratio. Ratios typically fall between 0 and .5 Flavor Aversion Learning Garcia – rats will not drink water with saccharin if they get ill after drinking. Significant avoidance occurs after just one trial. Human food aversions are related to illness (89%). Even if illness occurs hours later it is linked to the previous meal. Not cognitive – know food not to blame Conditions Affecting Acquisition Chapter 3, pages 48-69 Conditioning Paradigms Delayed conditioning – the CS onset precedes the UCS onset. Trace conditioning – the CS starts and ends before the UCS onset. Simultaneous conditioning – the CS and UCS occur together. Backward conditioning – the UCS starts and ends before the CS onset. Temporal Conditioning No CS is presented. The UCS occurs at regular intervals. A CR eventually occurs just before the UCS. Mechanism: a biological state typically provides the CS. Waking up just before the alarm goes off. Importance of Timing A cue (CS) needs to be a good predictor of the UCS. Optimal inter-stimulus-interval (ISI) varies with the kind of response. The latency to respond is different for different reflexes (saliva, heart rate) Too long or too short intervals result in weaker conditioning. Intermediate CS’s form a bridge. Importance of CS Strength CS intensity affects CR strength only when the CS intensity varies. If the CS strength is always the same, then the CS strength doesn’t affect the size of the CR. Both dogs must bite in order for their size to matter. In order for CS intensity to matter, it must signal something. Importance of UCS Strength Strength of the CR increases with strength of the UCS. The more intense the air puff, the stronger the eyeblink CR. Salience of the CS Salience refers to how noticeable a stimulus is – how likely an organism is to notice it in the environment. Preparedness (evolutionary predisposition) makes some CS more salient than others. The more salient the CS, the stronger the CR and faster learning. Predictiveness of the CS Predictiveness refers to how reliably the CS is associated with the UCS. When two or more CS’s are present, only the most reliable elicits a CR. When the CS occurs with the UCS more often than the UCS occurs alone, conditioning occurs. A CS alone weakens conditioning. Blocking Presence of a previously conditioned CS (existing predictive cue) prevents conditioning of a new CS. Parent threats – presence of fear of the parent prevents acquisition of fear to another stimulus. Implications for Parenting Threats (CS) should reliably be accompanied by punishment (UCS) or they will be ignored. Timing of threat (CS) and punishment (UCS) should be close together – not wait until Dad gets home. Fear of parents (CER) may block conditioning of any other CS.