Psychology 221: Intro. to Cog. Psych. Perception PDF

2025-01-14 Psychology 221: Intro. to Cog. Psych. Perception Thomas Spalek Week 2 Chapter 3 1 1  2025-01-14 Plan for...

2025-01-14 Psychology 221: Intro. to Cog. Psych. Perception Thomas Spalek Week 2 Chapter 3 1 1  2025-01-14 Plan for Today ▪ Input ▪ Sensory Memory ▪ Pattern Recognition ▪ Bottom-Up vs Top-Down Processing Psyc 221 2 2  2025-01-14 Information Processing Model Atkinson and Shiffrin (1968) Psyc 221 3 3  2025-01-14 Sensation vs. Perception Sensation: the reception of stimulation from the environment and the initial encoding of that stimulation into the nervous system Perception: the process of interpreting and understanding sensory information Psyc 221 4 4  2025-01-14 Input Psyc 221 5 5  2025-01-14 Photoreceptors Cones – Colour sensitive – Red – Green – Blue Rods – Luminance sensitive – achromatic (white-black) Psyc 221 6 6  2025-01-14 Distribution of Photoreceptors Psyc 221 7 7  2025-01-14 Refining the Input Photoreceptors -> Bipolar Cells Bipolar Cells -> Ganglion Cells Ganglion Cells -> Visual Cortex Psyc 221 8 8  2025-01-14 Saccades and Fixations Saccade: the quick movement of the eyes from one location to another saccades vary in duration (in part as a function of length) but often take about 25- 175 msec Fixation: the brief period when the eyes stop moving and process the visual scene fixations also vary in duration (e.g., in reading) but typically last 200 msec or less Psyc 221 9 9  2025-01-14 How much can you see in a single glance? Perceptual span (span of apprehension) : # of items that the individual can report from a brief display that did not allow for eye movements (i.e., less than 200 msec) Found to be approximately 4.5 items Psyc 221 10 10  2025-01-14 George Sperling (1960) his Ph.D. dissertation challenged the concept of limited perceptual span introduced the concept of iconic memory as a sensory store Psyc 221 11 11  2025-01-14 Sperling (1960) he replicated the standard perceptual span limitation of 4.5 items, as long as the display was less than an eye fixation (10- 200 msec) his subjects reported two “introspections”: – They claimed that they had actually seen the whole array, but “forgot” it while reporting – They claimed that the array seemed to fade but was available to examine mentally even after it went off the screen Psyc 221 12 12  2025-01-14 Exp. 1: Partial Report whole report = trying to report everything that was presented (i.e., perceptual span) partial report = trying to report only that portion of the display that is cued Sperling used 50-msec displays followed by tone cues Key question: Would 3 X partial report = whole report? https://www.youtube.com/watch?v=ACddnsfgJ7I Psyc 221 13 13  2025-01-14 Exp. 1: Predictions optimal performance 12 Number of Items Reported 100% of 12 letters 10 8 6 4 2 whole report ~ 35% of 12 letters 0 1 2 3 4 5 6 7 8 9 10 11 12 Number of Items Displayed Psyc 221 14 14  2025-01-14 Exp. 1: Data optimal performance 12 Number of Items Reported 100% of 12 letters 10 8 partial report 6 ~82% of 12 letters 4 2 whole report ~ 35% of 12 letters 0 1 2 3 4 5 6 7 8 9 10 11 12 Number of Items Displayed Psyc 221 15 15  2025-01-14 Exp. 2 only one array size (3 X 4) only partial report variable delay before the partial report signal logic: – if there is no icon, then any delay should eliminate partial report advantage – if there is an icon, the partial report advantage should decrease as that icon fades over time Psyc 221 16 16  2025-01-14 Exp. 2: Predictions 12 12 Number of Items Reported Number of Items Reported 10 10 8 8 6 6 4 4 2 2 0 0 -0.15 0.00 0.15 0.30 0.45 0.60 0.75 0.90 1.00 -0.15 0.00 0.15 0.30 0.45 0.60 0.75 0.90 1.00 Delay of Report Signal (sec) Delay of Report Signal (sec) No Icon Icon Psyc 221 17 17  2025-01-14 Exp. 2: Data 12 Number of Items Reported 10 partial report 8 whole report 6 4 2 0 -0.15 0.00 0.15 0.30 0.45 0.60 0.75 0.90 1.00 Delay of Report Signal (sec) Psyc 221 18 18  2025-01-14 Averbach & Coriell (1961) cued only one location to reduce memory demands even more (ultimate partial report!) replicated Sperling’s results using bar marker as cue but when they used a circle as the cue… Psyc 221 19 19  2025-01-14 Conclusions a lot is perceived in a single fixation perceptual span is not a good measure of what is perceived an iconic image persists after the display disappears this image, or “icon,” decays and is lost very rapidly Psyc 221 20 20  2025-01-14 Sperling (1960) Exp. 3 Question: What is the format of representation in iconic memory? mix letters and digits 3 kinds of report: – whole – partial – spatial (row) – partial – categorical (type) Psyc 221 21 21  2025-01-14 Exp. 3: Data partial spatial report (as in earlier experiments) was better than whole report partial categorical was no better than whole report Conclusion: all of the information in iconic store is very visual and quite unprocessed as to meaning = raw, sensory information Psyc 221 22 22  2025-01-14 Sperling (1963) Question: How quickly does pattern recognition copy information from sensory store to working memory? manipulate exposure duration of array from 5 msec to 200 msec but there was a problem…. Psyc 221 23 23  2025-01-14 Problem & Solution Problem: Question assumes you can only extract information during actual display, but we already know that isn’t true because of the icon Solution: Psyc 221 24 24  2025-01-14 Sperling (1963): Data Number of Items Recognized 8 7 6 5 4 3 2 1 0 10 20 30 40 50 60 70 80 Exposure Duration Before Mask (msec) Psyc 221 25 25  2025-01-14 Sperling’s Conclusions we can pattern recognize about 1 letter every 10 msec, up to a maximum of 5 Probably at least partly determined by the capacity of short-term/working memory Psyc 221 26 26  2025-01-14 Summary representation in sensory store is in terms of raw, sensory, uninterpreted information sensory store has a very large capacity, contrary to what the perceptual span suggests the duration of information in sensory store is very brief—1/4 to 1 sec (iconic), or 1 to 4 sec (echoic)—with forgetting via rapid decay transfer to Working Memory occurs via pattern recognition Psyc 221 27 27  2025-01-14 Pattern Recognition – Template Theories Template: a pattern treated as an unanalyzed whole e.g., numbers on cheques; universal bar codes Psyc 221 28 28  2025-01-14 Problems A Orientations/ Viewpoints A N Occlusion 2O5 Pattern Differences P Interpretations Psyc 221 29 29  2025-01-14 Feature Theories Feature: a separable element of a pattern a feature theory aims to describe a pattern by listing the elements of that pattern ties well to concept identification an example—letter recognition as done by Selfridge’s (1959) Pandemonium model Psyc 221 30 30  2025-01-14 Selfridge (1959) Psyc 221 31 31  2025-01-14 Bottom-up vs Top-down [bottom = sensory input; top = knowledge] Bottom-up: processing begins with the sensory input and ends with its representation. The outcome of a lower step is never affected by a higher step in the process Top-down: the output of a lower step is influenced by a higher one Psyc 221 32 32  2025-01-14 Direct vs Constructive Perception Direct perception theories – Bottom-up processing – Perception comes from stimuli in the environment – Parts are identified and put together, and then recognition occurs Constructive perception theories – Top-down processing – People actively construct perceptions using information based on knowledge and expectations Psyc 221 33 33  2025-01-14 Gestalt Principles of Perceptual Organization Rules governing how features should be put together Principle of similarity Similar things appear grouped together Principle of good continuation Lines tend to be seen as following the smoothest path Law of Pragnanz Every stimulus pattern is seen so the resulting structure is as simple as possible Psyc 221 34 34  2025-01-14 Helmholtz’s Unconscious Inference Our perceptions are the result of unconscious assumptions, or inferences, that we make about the environment Likelihood principle: we perceive the world in the way that is “most likely” based on our past experiences Psyc 221 35 35  2025-01-14 Regularities of the Environment Common physical and semantic properties of the environment Oblique effect – We perceive verticals and horizontals more easily than other orientations because we experience them more regularly Light-from-above assumption – We assume light comes from above because this is common in our environment Scene schema It is knowledge of what a given scene ordinarily contains E.g., Would you expect to see a plate of fish and chips or diamond rings in a display case at Tiffany’s Psyc 221 36 36  2025-01-14 Palmer (1975) Psyc 221 37 37  2025-01-14 Palmer (1975) Psyc 221 38 38  2025-01-14 Features in Context Psyc 221 39 39  2025-01-14 Bayesian Inference One’s estimate of the probability of a given outcome is influenced by two factors: – The prior probability – The likelihood of a given outcome Psyc 221 40 40  2025-01-14 Movement Facilitates Perception As observers, our movement adds complexity to perception compared to if we remain static, but moving around a stimulus offers us more views to create accurate perceptions. https://cargocollective.com/matthieu-robert-ortis/Video Psyc 221 41 41  2025-01-14 Difficulty in Designing a Perceiving Machine Inverse Projection Problem Infinite number of sources for any given retinal image Objects can be hidden or blurred Objects look different from different viewpoints Viewpoint invariance Scenes contain high-level information Scenes are more complex Psyc 221 42 42  2025-01-14 Too soon? Availabilty bias? Difficult to compare ~90% of crashes are due to human error autonomous statistics might be somewhat misleading Psyc 221 43 43  2025-01-14 Seeming ease leads to trivializing Psyc 221 44 44  2025-01-14 Perception is complicated Psyc 221 45 45