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Prism Adaptation Dr. Roger Newport Room B47. Drop-In Sessions: Tuesdays 12-2pm. Laura Condon Room A47. Mondays 1-2pm.

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Presentation on theme: "Prism Adaptation Dr. Roger Newport Room B47. Drop-In Sessions: Tuesdays 12-2pm. Laura Condon Room A47. Mondays 1-2pm."— Presentation transcript:

1 Prism Adaptation Dr. Roger Newport Room B47. Drop-In Sessions: Tuesdays 12-2pm. Laura Condon Room A47. Mondays 1-2pm.

2 Week 1: Introduction. Listen to introductory lecture. Get allocated to groups. Start researching literature. Begin planning experiment. Week 2: Pilot Study. Test and fine tune your experiment. Week 3: Experiment Week. Run your experiment. Week 4: Stats Analysis. Listen to stats talk. Perform analysis. Week 5: Presentation week. Tell everyone about your fascinating experiment.

3 This week Prism adaptation demonstration Prism adaptation explanation Hints and tips and dos and donts Stats preview Divide into groups Get on with it

4 This lab class needs YOU! Prism adaptation demonstration

5 T T T TT TT T How optical prism displacement works

6 The prism adaptation effect and the negative aftereffect TTT Adaptation 1st reach Later reaches Aftereffect Pretest

7 Prism adaptation: the 2 adaptation processes Perceptual recalibration (slow) Unconscious correction of sensory misalignment Probably involves cerebellum Visual straight ahead rotation Strategic control (fast) Probably involves PPC Conscious correction of visual error E E = expected hand position On-line correction Deliberate misreaching Recalibration of felt hand position to match visual shift

8 Perceptual recalibration Unconscious correction of sensory misalignment Negative aftereffect Only perceptual recalibration leads to the negative aftereffect Prisms offPrisms on The true test of prism adaptation is in the magnitude of the aftereffect Occurs despite knowledge of prisms removal not strategic control

9 Prisms: what are they good for? Studying motor learning Studying sensorimotor integration Studying cortical plasticity Rehabilitation Posterior Parietal Cortex Human imaging and patients Cerebellum Monkey and human lesions impair adaptation Premotor (vPM) impaired re-adaptation following inactivation (in monkeys)

10 PD = 100tan = (PD/100)tan -1 Prism dioptres 1m (100cm) PD = the amount of visual shift at 1m Technical stuff: What is a prism dioptre?

11 Wedge prism Fresnel prism Technical stuff: Types of prisms

12 Things that are important for prism adaptation Vision of the hand Knowledge of end-point error Speed of movement End-point corrections Speed between phases Rule of thumb: quickly executed rapid trials in which you only see your direction error towards the end of the movement gives the best adaptation

13 Things you must not do: Lose, damage or fail to return my prisms Use incongruent lenses (strength or direction) Leave subjects unsupervised Drive (and other obviously stupid things like DIY) Not recommended

14 Things you could manipulate: Transfer of adaptation from limb to limb Transfer from eye to limb Transfer between tasks/posture Passive vs active adaptation Terminal vs concurrent exposure Fast vs slow movements End-point error feedback Time/decay Cognitive interference Re-adaptation

15 Where does E-prime come into this? Your experiment MUST have an e-prime component E-prime options: Measurement of end-point error Presentation of adaptation stimuli

16 How a standard prism experiment might look Condition 1 Pre Exp (e-prime?) Post Condition 2 Pre Exp (e-prime?) Post We may only need to record the last few pre-exposure and the first few post-exposure in each manipulation

17 For this lab class your study should be a 2x3 repeated measures design Two factors: one with two levels one with three (pre, exp, post) You choose the factor with 2 levels Each participant performs ALL conditions

18 To analyse this experiment we will be using: planned comparisons We can use planned comparisons when we have specific predictions about the outcome of the experiment We only have to test our specific predictions and nothing else This makes analysis simple and honest.

19 Planned comparisons are essentially t-tests that take into account the variability of the all the data in the model. We will go into these in more detail in week 4, but it is important that when you plan your experiment you are aware of your predicted outcomes and how you will test them.

20 Simplifies analysis Reduces risk of type I errors P value correction not normally necessary Interpretation is easy as each comparison is derived from a specific hypothesis No tricky interactions to interpret Only have results that you are interested in Advantages of planned comparisons: Disadvantages: SPSS does not (easily) do the comparisons we need

21 What do we really want to know? What are our hypotheses? Why are we doing this experiment?

22 Planned comparisons What do we really want to know? What are our hypotheses? Why are we doing this experiment?

23 What to do now Divide into groups Collect and sign for your prism goggles Get on with it Play with prisms Read some background literature Start planning experiment B A D C E


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