MBB1 EXAM - SENSATION & PERCEPTION

What was Posner’s study?

Attention speeds responses - 'fixation box w/ arrow, had to click where X was. Longest response time when X was on the opposite side of the box

What was the study by Carrasco et al.?

• attention makes perception have a higher contrast

• fixation cue moves/expands to attention drawn to fixation cue.

• Findings: participants who had their attention drawn to one side due to the movement of the fixation cue reported that the grating on that side had higher contrast

What did Treisman & Schmidt study?

• illusory conjunctions as part of FIT, where inhibition of attention causes incorrect binding of features from different objects (part of the binding problem)

• brief presentation of character strings for 95-168 ms followed by noise mask → participants often associated the wrong colour w/ the wrong letter

• RM w/ parietal lobe damage Balint’s syndrome → reported wrong letter-colour combinations for 23% trials

  • prone to illusory conjunctions b/c he could not focus his attention on just a single object

What did Potter study?

• Gist perception

• observer cued w/ particular scene description → shown 16 randomly chosen scenes for 25 ms

• asked if any scenes matched description → almost 100% accuracy

• Finding: observers can rapidly perceive a scene’s gist

What did Fei-Fei et al. study?

• minimum scene exposure time needed to perceive a scene gist

• single scene presented followed by a mask → participants described what they saw

• Finding: the longer the stimulus presentation time, the more detailed & accurate the description

  • people could start to perceive aspects of a scene @ 27 ms, but very accurate perceptions could be achieved @ 250 ms

What did Robert Adams study?

• motion aftereffects; waterfall illusion

What is Korte’s Third Law of Apparent Motion?

for apparent motion to occur, as separation increases, alteration rate needs to decrease

What did Bonner, Cooperman & Sagi study?

• motion-induced blindness: movement of blue crosses while fixating on green dot made yellow dots disappear

What did Suchow & Alvarez study?

• motion-induced change blindness

• colour changes less apparent when dots are moving

Describe protanopes

• do not have L cones

• cannot distinguish b/w red & green

• can distinguish b/w blue & green, & blue & red

• see world in shades of blue & a yellow-green

Describe deuteranopes

• do not have M cones

• cannot distinguish red & green

• can distinguish b/w blue & green, & blue & red

• see world in shades of blue & a yellow-green

Describe tritanopes

• do not have S cones

• can’t distinguish b/w blue & green (cannot see yellow)

• can distinguish b/w red & green, & blue & red

What is the equation for reflected light

reflectance x illumination

What are the 2 ways that the visual system achieves colour constancy?

• Habituation

• Discounting the illuminant

What are the 3 types of cues to perceive depth

• oculomotor cues: cues based on the ability to sense the position & state of our eyes

• monocular cues: cues based on the visual information available within an eye

• binocular cues: cues that depend on visual information within both eyes

What are the 2 types of occulomotor cues?

• binocular convergence

• accommodation

What are the 3 main types of monocular cues?

• accommodation

• pictorial cues

• movement-based cues

What is the main type of binocular cue?

binocular disparity → relative & absolute disparity, & the correspondence problem

What are the 7 types of pictorial cues?

• occlusion

• relative height

• familiar & relative size

• perspective convergence

• atmospheric perspective

• texture gradient

• shadows

What are the 2 types of movement-based cues?

• motion parallax

• deletion & accretion

What did Holway & Boring study?

• how observers accurately estimate the size of objects

• condition 1 & 2 w/ sufficient depth cues → test patch accurately estimated

• condition 3 & 4 w/ insufficient depth cues → test patches perceived smaller than they really are b/c apparent size of test patch was biased towards the visual angle

What are the 4 components of architectural acoustics?

• reverberation time

• intimacy time

• bass ratio

• spaciousness factor

what are the 5 components of auditory organisation?

• location

• onset time

• timbre & pitch

• auditory continuity

• experience

What did Rensik et al. study?

The need for attention to perceive changes in scenes

What is the general summary of the results by Rensik et al?

• Low-level cues that draw attention are swamped → large changes in images of real-world scenes become extremely difficult to identify, even if the changes are repeated dozens of times & observers have been told to expect them.

• changes are easily identified when a valid verbal cue is given, indicating stimulus visibility is not reduced

• changes easily identified when made to objects considered to be important in the scene

What is the main finding of Rensik et al.’s study"?

• an observer does not build up a representation of scene that allows them to perceive changes automatically

• perception of change is mediated through a narrow attentional bottleneck → attention is attracted to various parts of a scene based on high-level interest

What was the hypothesis for study 2 of Rensik et al.?

Saccade-contingent change blindness may not be due to saccade-specific mechanisms, but rather may originate from a failure to allocate attention correctly

• transients play a large role in drawing attention

What was the general method of Rensik et al.’s paper?

• A. A, A’, A’ … w/ grey blank fields placed b/w successive images (degree of temporal uncertainty as to when the change was being made)

• each image displayed for 240 ms & each blank for 80 ms

What were centra interests & marginal interests in the study by Rensik et al.?

• Central interest (CI): objects of areas mentioned by three or more observers

• Marginal interest (MI): objects or areas mention by no observers

What was the dependent variable for Rensik et al.’s studies?

DV: average number of alterations (proportional to the reaction time) needed to see the change

*averages only taken from correct responses

What did experiment 1 of Rensik et al. investigate & what were the findings?

• Whether the basic flicker paradigm could induce change blindness

• Predictions:

  • Insufficient viewing time for change blindness (brief-display experiments) → changes in the experiment to be seen within a few seconds of viewing

  • saccade-specific mechanisms responsible for change blindness (saccade experiments) → changes to be easy to see by keeping eyes still

  • change blindness due to attention mechanism (flicker conditions) → changes under flicker conditions would take a long time to see

• Results:

  • flicker conditions: changes in MI extremely difficult to see, changes in CI noticed much more quickly

What did experiment 2 of Rensik et al. investigate & what were the findings?

• Hypothesis: old & new scene descriptions could not be compared because of time limitations

  • Prediction: if memory process = limiting factor, longer display of images → consolidation to take place → changes easily seen

• A, A’, A, A’ (shown for 560 ms each)

• Findings: slight speedup for MI interest, response times for MI & CI for all 3 kinds of change not significantly different from counterparts in Experiment 1

What did experiment 1 of Rensik et al. investigate & what were the findings?

• repeated experiment 1 but w/ verbal cue placed in white rectangle for 3 seconds @ beginning of each trial

  • Partially valid conditions:

    • half valid cues (named the part of scene changed)

    • half invalid cues (named another part)

  • Completely valid condition: always valid cues

• hypothesis: flicker reduces the visibility of items in the image to the point where they simply become difficult to see

  • Prediction: visibility = limiting factor → not large effect of cuing should have occurred; target would remain difficult to find. Visibility is NOT limiting factor → valid cues improve performance, not affected by invalid cues

• Results: valid cues always caused identification of both MI & CI changes to be greatly sped up (significant for both conditions)

  • completely valid conditions: difference in response item for MIs & Cis declined → no longer significant

    • indicates that the faster performance for CIs in experiment 1 is unlikely to be due to simple salience of their features

What were the final proposals by Rensik et al?

• visual perception of change in an object occurs only when that object is given focused attention

• absence of focused attention → contents of visual memory are overwritten by subsequent stimuli → cannot be used to make comparisons

What were the conclusions of a saccade-contingent change in Rensik et al.’s study?

most (all) of the blindness to saccade-contingent change is simply due to the disruption of the retinal image during a saccade, causing swamping of the local motion signals that would normally draw attention

Which depth cues can indicate absolute depth at 0-2 metres?

• size of the retinal image

• motion parallax

• accommodation

• convergence

Which depth cues can indicate absolute depth at 2-20 metres?

• size of the retinal image

• texture gradients

• motion parallax

Which depth cues can indicate absolute depth at > 20 metres?

• size of the retinal image

• texture gradients

What depth cue can indicate relative depth @ 0-2 metres?

occlusion

What depth cues can indicate relative depth @ 2-20 metres?

• occlusion

• deletion & accretion

• relative height

What depth cues can indicate relative depth @ > 20 metres?

• occlusion

• deletion & accretion

• relative height

• atmospheric perspective