Week 2 (Change Blindness) Flashcards
Perception recap
-Distinction drew between sensation and perception
-How we perceive the world around us can be influenced by our minds
Bottom-up VS Top-Down
-Bottom-up processing (Driven by environment)
-Top-down processing (Driven by our minds)
Four functions of attention
-Signal detection
-Visual search
-Selective attention
-Divided Attention
Visual search and selective attention
-Focused attention needed if the thing we were looking for differed from objects around it on more than one dimension
Dichotic listening task
-Presenting two messages to different ears and seeing which one breaks into conscious attention
-Participants filtered out information presented to the unattended ear
-Filtering might be performed based on physical properties (location, tone, pitch) with some hint meaning could also play a role.
Neisser
Neisser (1979)
-Wide range of experiments
-Involved two videos shown over each other using mirrors
-Participants had a task that oriented them to the display
-Unexpected event occurs
-Inattentional blindness
Simons & Chabris (1999)
The gorilla experiment, investigates
-Visual similarity (How similar the unexpected event is to the task)
-Task difficulty (How many attentional resources are needed)
-Medium (Superimposed VS Live)
-The nature of the event (Umbrella woman VS gorilla)
Mack and Rock (1998)
-Tested inattention blindness under lab conditions
-Paradigm includes fixating on the centre of a cross, and deciding which of its two arms are longer
-On the 3rd or 4th trial an unexpected object is shown within a quadrant of the cross (25% missed it)
-When object placed in the middle, 60-70% missed it
Conclusion from inattentional blindness studies
-Attention appears to be essential for perceiving
-When you attention is focused on another task you will miss unexpected events
-Particularly true for those that are dissimilar to the items in the task you are focusing on
Limitations of investigating inattention blindness
-Investigating inattention blindness is very challenging
-Expectations affect the result, so there is only ever one critical trial, and therefore one data point
-Inattentional blindness tasks are therefore very fast but require a lot of participants
-Also rely on self report, so conclusions are limited to “within conscious awareness”
Change Blindness
Failure to notice a change in a visual scene
-Continuity errors in films are classic examples of change blindness
-Unlike inattention blindness, it doesn’t matter if you know there will be a change, the task is still hard unless you know where to look
What are the stages involved in change blindness
-Focused attention on the relevant location
-Encoding in memory the information in this location before the change
-Encoding in memory the information in this location after the change
-Comparing the two representations
-Consciously detecting the difference between the memory and visual experience
Rinsing et al (1997)
-Created the flicker task for change blindness
-Blank screen in between masks small changes so participants don’t notice any motion signals
-Without flicker: average was 1.4 alternations to notice change
-With flicker: average was 7-17 alternations
-Changes in marginal interest took longer to indentify than those of central interest
Inattentional Blindness Vs Change Blindness
- IB is affected by expectations, but CB isn’t
- IB requires observers to be engaged in a demanding primary task (divided attention) but CB doesn’t
- CB involves memory processes as well as attention and perception, but IB doesn’t.
Real world application of change blindness
-Driving accidents, failing to look, but also, looking but failing to see
-Galpin et al (2009) extended these phenomena to road scenes
-Semantic relevance was important, but it seemed to interact with location
-Curiously changes with no semantic relevance that were central to the view were noticed less often, and driver experience was not important
Beanland et al (2017)
-Compared rural/urban safety relevance
-Less errors in rural environments
Filtness et al (2020)
-Investigated if change blindness when driving was related to sleep loss (it wasn’t)
Real world application of inattentional blindness
Eyewitness testimony
-Witnesses to crimes don’t always know that they are about to witness one
-May be attending to something else in the environment
-Leads them to miss crucial details
Rivardo et al (2011)
-Participants watched video that included theft
-Some told to just watch, some had to do a counting task
-90% noticed without the task, 19% noticed with the task
Cullen et al (2017)
-Watched scene for bus to appear, missed girl being kidnapped
Chabris et al (2011)
-Participants chased an experimenter (irl) and missed a physical assault taking place nearby
Simons & Schlosser (2017)
-Trainee police officers less likely to spot a gun in a simulated traffic spot.
