PSYC 414- Generalization & Discrimination

generalization

the transfer of past learning to novel events and problems

discrimination learning

the process by which animals or people learn to respond differently to different stimuli

concept formation

the process by which we learn about new categories of entities in the world, usually based on common features

generalization gradient

a curve showing how changes in the physical properties of stimuli correspond to changes in responding

• show a peak that corresponds to the original stimulus on which the animal was trained

• can preict based on past experience the likelihood that consequence of one stimulus will be the same as another stimulus

consequential region

a set of stimuli in th world that share the same consequence as a stimulus whose consequence is already known

stimulus representation

the form in which information about stimuli is encodd within a model or brain

discrete-component representation

a representation in which each individual stimulus (or stimulus feature) corresponds to one element (node) in the model

• a simple network model that has a single input node for each of five possible colors of light

• doesn’t show a a smooth generalization gradient like that shown by the pigeons

problems with discrete-component representations

they fail in cases where stimuli have a high degree of physical similarity, since the models produce unrealistic generalization gradients

distributed representation

a representation in which information is coded as a pattern of activation distributed across many different nodes

• “yellow” representation would be across many nodes

• associativ weights between internal nodes and output nodes

stimulus control

the influence of cues in the world on an organism’s behavior

discrimination learning (pigeons)

• one group of pigeons trained to respond to a 1,000 Hz tone with a key peck for food

• second groupd trained to respond to 1,000 Hz, but response to 950 Hz would mean no food

interdimensional discrimination

the two stimuli in this experiment (pigeons with tones) differ within a single dimension

extradimensional discrimination

when animals learn to discriminate between stimuli that differ across multiple dimension (such as tones and lights)

errorless discrimination learning

a training procedure in which a difficult discrimination is learned by starting with an easy version of the task and proceeding to incrementally harder versions as the easier ones are mastered

sensory preconditioning

training in which presentation of two stimuli together as a compound results in a later tendency to generalize what is known about one of these stimuli to the other

Separate exposure

• tone and light separately

  • light —> airpuff and blink, tone = no blink

compound exposure

• tone and light together

  • light and tone cause blink

outcome-based generalization

occurs in third phase of sensory preconditioning, the animal generalizes the light to the tone

acquired equivalence

a learning and generalization paradigm in which prior training in stimulus equivalence increases the amount of genralization between two stimuli, even if those stimuli are superficially dissimilar

• pecking in phase 2 not given food for, B1 disk which leads to no strong response in phase 3

negative patterning

a behavioral paradigm in which the appropriate response to individual cues is positive, whereas the appropriate response to their combination (pattern) is negative (no response)

tonotopic representation

spatial arrangement of where sounds of different frequency are processed

• low to high frequency gradient from one end of primary auditory cortex to the other

Richard Thompson

established a direct relationship between behavioral properties of auditory generalization and certain anatomical and physical properties of the auditory cortex

• animals with lesions to primary cortex, still respond, but causes overgeneralization

Cerebellar Circuits for Conditioning

pontine nuclei receives input from diff cortical areas including auditoru cortex,

• mossy fiber pathway from Pontine nuclei to Granule cells in Cerebellar cortex sends collaterals to interpositus nucleus

anatomical loop

1. auditory cortex

2. pontine nucleus

3. cerebellum

4. deep cerebellar nuclei

5. thalamus

6. auditory cortex

cortical remapping

after training, the responses of an auditory cortex neuron changed from being most responsive to a 1,000 Hz tone to being most responsive to tones nearer to the training frequency

nucleus basalis

a small group of neurons located in the basal forebrain; these neurons deliver acetylcholine to the cortex

• tone paired with nucleus basalis electrical stimulation results in cortical remapping

• acetylcholine is important for cortical plasiticity

basal forebrain

damage to this causes anterograde amensia, inability to form new semantic and episodic memories

Hippocampal region

learning about relationships between stimuli in the environment is part of the special role

• sensory preconditioning is blocked in animals with lesions to the hippocampus

neophobia

fear of new things