Week2

Timing and Time Perception

  • Course: COGS2000, Week 2

Degrees of Time Perception

  • Perception of time: varies significantly; influenced by different factors.

  • William James: introduced the concept of the 'saddle of the present', which highlights how the perception of time can be fluid.

  • Flicker Fusion: describes the break in perception when rapid stimuli create a sense of continuity.

Types of Timing

  • Two types of timing:

    • Retrospective Timing: remembering duration after the event.

    • Prospective Timing: tracking time during an event.

  • Implicit vs. Explicit Timing:

    • Implicit involves subconscious awareness of time; explicit involves conscious measurement and awareness of time.

    • Timing often involves waiting for a response after perceiving an event.

Tasks for Timing

  • Key tasks involved in timing include:

    • Bisection, reproduction, production, temporal generalisation.

      • Each task has different requirements for memory and attention.

    • Simultaneity Judgments: determining whether events occurred together.

    • Temporal Order Judgments: discerning the sequence of events.

    • Passage of Time Judgments: how we perceive time passing during different contexts.

    • Highly contextual and sensitive to variables like when the questions are posed.

    • Time-tradeoff Judgments: evaluation of how time affects choices, such as monetary decisions.

Temporal Discounting

  • Example of Delay Preference:

    • Choosing between different monetary rewards over time (e.g. $10 today vs. $12 tomorrow).

  • Calculation of values:

    • Comparison allows assessment of value of time versus money and consistency in decision-making related to time.

  • Real-world scenario: Trading time in online driver training for avoiding fines.

Brain Hypotheses in Delay Discounting

  • Hypothesis Exploration:

    • What brain activity occurs during delay discounting tasks?

    • Considerations include:

      • Future self-projection

      • Delayed gratification

      • Self-control analysis.

fMRI Insights

  • General Points:

    • Correlational Data: fMRI results are correlational, not causal.

    • Temporal Limitations: fMRI samples are relatively slow (around 1 second).

    • Technique: Images generated using the magnetic properties of molecules.

MRI Imaging Process

  • Static Magnetic Field Application:.

    • Aligns hydrogen atoms to a common plane.

  • RF Pulse Application:

    • Alters the alignment of hydrogen atoms enabling imaging based on how they resonate after pulses.

Generating an Image (Steps)

  1. Initial 90° RF pulse aligns protons.

  2. Protons begin to dephase after the pulse is removed.

  3. At mid-time (TE/2), a 180° RF pulse flips their orientation.

  4. Protons oscillate to a maximum when they are back in phase, producing an echo for imaging.

Insights on Temporal Discounting

  • Brain Activity during Decision Making:

    • Decreased brain activity in specific regions indicates less preference for delayed rewards.

    • Regions affected include:

      • Left inferior frontal gyrus (IFG)

      • Ventral striatum (VS)

      • Anterior cingulate cortex (ACC) and medial prefrontal cortex (mPFC).

  • Comparisons made between healthy individuals and those with addiction issues.

Neuroanatomy of Timing

  • The correlation of timing decisions in brain regions:

    • Two systems of decision making (objective value vs. subjective).

    • Different brain areas engaged in processing timing and decision-making.

Simultaneity Judgement Tasks

  • Nature of tasks: Determine the order and simultaneity of sensory experiences (speed of light vs. sound).

  • Critical Differences in Perception Times:

    • Light takes longer to reach the brain than sound, resulting in perceptual lags.

Variable Foreperiods and Temporal Expectations

  • Use of variable foreperiods relates to temporal expectations aiding learning over time without formal judgments.

  • Key Features of the Task:

    • Hazard function and carryover effects based on previous trials.

(M)EEG Measures

  • How (M)EEG monitors brain activity through electrical activity from neurons.

  • Recognized for high sample rates compared to other modalities like fMRI.

Impact of Contextual Variables on Timing

  • Factors affecting time perception include:

    • Temperature

    • Attention

    • Memory

    • Task difficulty

    • Age

    • Psychological conditions and emotions.

Potential Clocks in the Brain

  • Evidence suggests multiple areas can keep time, particularly:

    • Auditory information perceived as lasting longer than visual.

    • Roles of regions like hippocampus, cerebellum, and striatum need further investigation.

Complex Models of Time Perception

  • Current biological models highlight dopamine's role in timing, integrating different neuronal pathways for processing events.

  • Cortex and Thalamus Integration:

    • Coordination between areas enables the brain's timing capabilities.

Questions for Further Exploration

  • Open to queries regarding the neurological underpinnings of timing perception and the models presented.