Memory is deceptive because it is colored by

“Memory is deceptive because it is colored by today's events. ” (Albert Einstein) David Hadas, CS TAU Under the supervision of: Prof. Nathan Intrator, Dr. Galit Yovel

Agenda • Distinction – The magical number 7 – Multidimensional stimulus identification • Recognition – RBC • Memory – Effects of temporal association on recognition memory – Morphing visual memories through gradual associations • Our research – Working memory – Long term memory • Identifying object classes • Discrete vs. Continuous memory – Current work

The magical number seven George A. Miller (1956) • For unidimensional judgments: The “span of absolute judgment” is ~7 • We can improve by: – Making relative judgments – Increasing dimensionality – Using successive judgments 3 bits In 2. 5 bits Communication Channel Out Source: Pollack 1952, 1953

Multidimensional stimulus identification Egeth Pachella 1969 • Slower • More error prone • Speed and Accuracy decline with dimensionality It takes time to measure! Than how do we identify objects in 100 ms?

Recognition By Components (RBC) Irving Biederman (1987) • Primal Access – Memory Access – “The first contact of perceptual input from an isolated unanticipated object to a representation in memory” Symmetry Curvilinearity Collinearity Parallel Curves Vertices Edge Extraction Detect non-accidental properties Detect Regions and Concavity Component Determination Region Geon Matching & Identification

Recognition By Components • 36 Geons suggested (Cont’)

Effects of temporal association on recognition memory G. Wallis, HH Bulthoff 2001 We are continuously associating views of objects to support later recognition.

Morphing visual memories through gradual associations S. Preminger, D. Sagi, M Tsodyks (unpublished) • How exposure to face stimuli, associated with a previously memorized face , influences the long-term memory of the stored face”

Our Research

Storing a representation • We cannot memorize what we cannot perceive • We can only store what we have in our working memory Representation in Long Term Memory Store Limited Perception Limited ability to represent in memory Representation in Working Memory

Recalling a representation • We cannot recall what we cannot perceive • We can only recall what we have in our working memory • Do we store as we retrieve? Representation in Long Term Memory Search Retrieve (Store) Limited Perception Limited ability to represent in memory Representation in Working Memory

Working memory • We have limited ability to measure • Can we at least maintain a measurement?

Test your working memory • Find the longest line We cannot remember a measurement! Jump to next test The Test Ended

Study the size of this circle Jump to next test (1)

How many circles of the same size do you see? Jump to next test (1) The Test Ended

Results Jump to next test (1) Why was this test successful?

Study the size of this circle Jump to next test (2)

How many circles of the same size do you see? Jump to next test (2) The Test Ended

Results Jump to next test (2)

What is the difference between the tests? • In the second test: – All circles are small – We modify the internal representation based on the stimuli Stimuli Jump to next test Stimuli

A representation in working memory • Depending on the memory type; – We have limited ability to reliably store even a single memory – We change the representation based on the stimuli Representation Limited Perception Limited ability to represent in memory Representation in Working Memory

Long term memory • We seem to have a slight working memory problem – We cannot reliably remember even a single dimension • Can we at least trust our long term memory to help out?

How detailed is our long term memory? • Can you describe a table? • Can you describe your table at home? – How do you remember it? • Can you describe Clinton? – How do you remember him? Classes: Class A Class B Class C Objects: A 1 A 2 A 3 A 4 B 1 B 2 B 3 B 4 C 1 C 2 C 3 C 4

We remember discretely • Discrete – – – – – Parallel or not Symmetrical or not Collinear or not Curvlinear or not Type of vertex Number of edges Number of vertices Certain Components Certain component arrangements • Continuous – – Length/Width/Depth Angle Ratio Color • Semi-Discrete – ~7 Categories (? ) – Categories of: • • Length/Width/Depth Angle Ratio Color

A representation in long term memory • We can only store what we have in our working memory – We change the representation based on the stimuli • • We seem to store as we search our long term memory Representation in Long Term Memory As a result: – Our long term memory is adaptive – We cannot rely on it for continuous measurements Search Retrieve (Store) Representation Limited Perception Limited ability to represent in memory Representation in Working Memory

Current work Protocols and measurements for tuning of the brain neural network • We develop a tool and a technique for qualifying and quantifying the plasticity shown during stimuli morphing • We study: – The brain inability to secure preset object representations – The brain natural and involuntary tendency to modify such representations based on stimuli – The affect of a protocol on the internal representation • We measure plasticity of subjects exposed to a morphing protocol • We characterize the affecting protocol and the resulting changes

Could it be that Einstein was right after all? When he said: “Memory is deceptive because it is colored by today's events. ” (Albert Einstein) 2 E=MC