1. Auditory Motion Or how I learned to stop worrying and love collisions

2. TLA 8: Cell Phone Driving Purpose to learn about auditory distraction Purpose to learn about auditory distraction Ingredients: Ingredients: Cell phone Cell phone Willing and/or helpful friend Willing and/or helpful friend Car Car Activity Activity While driving have a friend explain to you the plot of the last thing they read (e.g., book, magazine article) While driving have a friend explain to you the plot of the last thing they read (e.g., book, magazine article) Conversation over cell phone Conversation over cell phone While a passenger in your car While a passenger in your car Write Up Write Up Which is easier to follow? Why might these scenarios differ? Which is easier to follow? Why might these scenarios differ? Alternative Ingredients: Alternative Ingredients: Observation point of busy stop sign intersection Observation point of busy stop sign intersection Alternative activity Alternative activity Watch the first 3 cars with no cell phone and the first 3 drivers with a cell phone Watch the first 3 cars with no cell phone and the first 3 drivers with a cell phone Tally how many of each group look both ways before entering the intersection Tally how many of each group look both ways before entering the intersection Write Up Write Up Was there a difference in safety behavior for these two groups? Was there a difference in safety behavior for these two groups?

3. Do we hear auditory motion? Snapshot theory of motion (Grantham, 1990) Snapshot theory of motion (Grantham, 1990) No motion; successive perceived positions No motion; successive perceived positions Perception of motion is derived from landmarks Perception of motion is derived from landmarks Allows detect of spatial displacement Allows detect of spatial displacement Does not differentiate steady-motion from accelerating motion Does not differentiate steady-motion from accelerating motion Tests of the snapshot theory Tests of the snapshot theory Listeners can detect acceleration (Perrott et al., 1992) Listeners can detect acceleration (Perrott et al., 1992) Perceived displacement is influenced acceleration Perceived displacement is influenced acceleration Listeners do detect auditory motion Listeners do detect auditory motion

4. Auditory Time-to-Arrival Paradigm: Judgments of approaching objects Paradigm: Judgments of approaching objects Determine the moment an approaching object is closest Determine the moment an approaching object is closest Margin-of-safety Margin-of-safety Underestimation of approach trajectories Underestimation of approach trajectories Collision detection Collision detection Approaching object on crash course with listener Approaching object on crash course with listener Sighted listeners more accurate visually than auditorily Sighted listeners more accurate visually than auditorily Blind listeners/trained sighted listeners demonstrate highest accuracy judging collision (Rosenblum et al., 2000; Schiff & Oldak, 1990) Blind listeners/trained sighted listeners demonstrate highest accuracy judging collision (Rosenblum et al., 2000; Schiff & Oldak, 1990) Passage detection Passage detection Approaching object on near-miss or oblique trajectory Approaching object on near-miss or oblique trajectory Judgments are more accurate for passage than collision Judgments are more accurate for passage than collision

5. Potential Sources of Information for Auditory Motion Change in intensity over time Change in intensity over time Acoustic tau:  = - 2 I / (dI/dt) – no need to memorize this Acoustic tau:  = - 2 I / (dI/dt) – no need to memorize this Instantaneous rate of change in intensity over time Instantaneous rate of change in intensity over time Exponential increase in intensity over approach Exponential increase in intensity over approach Asymptote of intensity at the position of the listener Asymptote of intensity at the position of the listener Provides exact information about the moment of closest position/collision Provides exact information about the moment of closest position/collision Assumes constant intensity Assumes constant intensity Constant velocity Constant velocity Bats demonstrate sensitivity to acoustic tau Bats demonstrate sensitivity to acoustic tau

6. Potential Sources of Information for Auditory Motion Spectral content Spectral content High frequencies more easily attenuated than low frequencies High frequencies more easily attenuated than low frequencies Tau varies across frequency Tau varies across frequency Relative change in spectral content across the hearing spectrum Relative change in spectral content across the hearing spectrum Exponential increase in high frequencies during approach Exponential increase in high frequencies during approach Döppler Shift Döppler Shift Phenomenal change in pitch over time Phenomenal change in pitch over time Relative distance between sound waves decreases for an approaching object Relative distance between sound waves decreases for an approaching object Fairly constant rise in pitch Fairly constant rise in pitch Dramatic change near listener, little change over approach Dramatic change near listener, little change over approach Interaural position Interaural position Objects farther in distance tend to be less lateralized Objects farther in distance tend to be less lateralized Change in lateralization over passage Change in lateralization over passage