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Delays and Time Perception Mind and Life/Life and Mind Seminars 18.04.2007 Marieke Rohde.

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Presentation on theme: "Delays and Time Perception Mind and Life/Life and Mind Seminars 18.04.2007 Marieke Rohde."— Presentation transcript:

1 Delays and Time Perception Mind and Life/Life and Mind Seminars Marieke Rohde

2 Structure 1.Where do I come from? 2.Work so far The experiment The model 3.Time and Delays, revisited

3 1.) Where do i come from?

4 Background Cunningham et al. (2001): Adaptation to visual delays (200ms) in a reactive task. Negative aftereffect: –performance breakdown if delay was removed –„The plane seemed to move before the mouse did – effect appeared to come before the cause.” Sensorimotor disruptions shapes temporal experience (origins of time???) Piaget, Kant, Husserl, Heidegger, Merleau- Ponty,... Romi, GSP, GOFN,...

5 Experiments with delay –Recalibration of Audiovisual –Stetson et al.: Illusory reversals in the timing of actions and sensation –No adaptation in reading/drawing tasks –Surgery, lever pressing, …

6 Libet participant to siting at a desk in front of the oscilloscope timer. They would affix the EEG electrodes to the participant’s scalp, carry out some small, simple motor activity, such as pressing a button, or flexing a finger or wrist, within a certain time frame. And remember dot position By comparing the marked time of the button's pushing and the subject's conscious decision to act, researchers were able to calculate the total time of the trial from the subject's initial volition through to the resultant action. On average, approximately two hundred milliseconds elapsed between the first appearance of conscious will to press the button and the act of pressing it. Researchers also analyzed EEG recordings for each trial with respect to the timing of the action. It was noted that brain activity involved in the initiation of the action, primarily centered in the secondary motor cortex, occurred, on average, approximately five hundred milliseconds before the trial ended with the pushing of the button (readiness potential).

7 2.) What i‘ve done so far

8 My Experiments in Compiegne Try to find minimal experimental conditions that produce this effect and distinguish them from one‘s that don‘t Dynamically analyse sensorimotor behaviour and adaptation „Tactile pacman“ Main hypothesis (from Cunningham et al.): it‘s time pressure Thanks to: Olivier Gapenne Charles Lenay Dominique Aubert John Stewart

9 Protocol Expérimental Vitesses des objets variable pour éviter une interprétion comme deplacement vertical constant 4 phase, on compare la même séquance: –familiarisation/pretest (sans retard) –Mésurement de la perturbation par le retard (avec retard) –Entraînement/mésure d‘amelioration (avec retard) –Posttest (sans retard) Retard: 250ms (plus des details techniques besoin...) 19 sujets, 3 groups des vitesses testé, selon performance

10 Adaptation au délai (prédite) Avant entraînement Après entraînement Avec délai Sans délai Avec délai

11 Resultats dans le pilotage Ce n‘est pas trop évident que ca ne marche pas... „Mais c‘est plutôt une avance, maintenant...“

12 Some variables more interesting than others (# of crossings, time to stabilise) Some subjects more interesting than others Taxonomy based on some measures/visual appearance of trajectories How to formalise? Velocity, accelaration, crossings, direction, distance, centering, object velocities, … …or any combination of these… …in any sub-group of subjects. Where do I start??? Results

13 Analyse des trajectoires individuelles 19 individuals Adaptation Resistant (4) (pre = post) One Mode (2) Two Modes (2) Some kind of adaptation (15) (pre != post) Immediate (4) (no training effect) Adaptation (11) (training) Confusion (2) Improvement (2) Revert change perturbs (4) Training effect lasts in post (7) Slower (2)Faster (2) Better/ equal (6) worse (1)

14 ER Model Evolve agents to solve the task –With delay –Without delay Performance only perturbed if you add delay – at first glance Modified fitness worked – in theory! Displacement depending on velocity, only reflex like movements possible  time window  granularity of time

15 3.) Future

16 Kinds of sensorimotor loops Feedback/temporal correlation meaningless: Stetson et al., others Reactive: like high inertia (kite, boat) – drawing, surgery Constant velocity: like fixed spatial offset (my initial, maybe Cunningham initial?) Variable velocity fast: Cunningham, church organ?

17 What to do next Simplify data (maybe similar things irrelevant as in simulation?) Displacement in dependency of movement velocity Classify strategies –Random –Reactive –Reflex-like Robust vulnerable

18 So where does time come from? New hypothesis: –time pressure  act fast (no high inertia) –Pressure to vary velocity  no spatial offset (high predictability required) Time vs. space Granularity of time Multimodal integration of simultaneity I only know what i do once I’ve already done it –Illusionary motion, flash lag, …


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