Introduction to Cognitive Psychology

What is Cognitive Psychology?

• Cognitive psychology is the study of mental processes

What is Cognitive Psychology?

• Cognitive Psychology versus Behaviorism – Behavioral Psych: how S maps onto R – Cognitive Psych: what happens in the mind – Both can use formulas to map S onto R – The difference is level of complexity Environment S R Mind

What is Cognitive Psychology?

• Cognitive Psychology versus Neurobiology – Neurobiology: how does the brain do it?

– Cognitive Psych: how does the mind do it?

– Both can use neurons to describe mind – The difference is behavior (the big picture)

What is Cognitive Psychology?

• Metaphor: mind = Windows – Behaviorists: • “What happens when I press Alt-Tab? Cool! It switched to my last open application!!” But how does that work?

– Neurobiologists: • “Check this out, the harddrive and the RAM are both connected to the motherboard!” But what does that mean?

– Cognitive Psychologists: • “Pressing Alt-Tab switches me between applications, and I know that Windows uses STM… Let’s propose a model of Windows where it stores which apps are open in STM, and when a user hits Alt-Tab, it switches between open apps.”

What is Cognitive Psychology?

• Cognitive Psychology versus Artificial Intelligence (AI) – AI: what’s the best way to do this?

– Cognitive Psych: how do humans do this?

– Both try to model some form of mind – The difference is fidelity – Brain is optimal: If AI truly wants to find optimality they should study Cognitive Psychology.

Why study Cognitive Psychology

• Understanding the mind • Education • Medicine • Therapy • Artificial Intelligence • Tool/Interface Design • Gaming/Entertainment • Etc.

What is involved in Cognition

• The book lists: – Perception, Attention, Memory, Problem-Solving, Language, Reasoning, & Decision-making • This is not a comprehensive list of mental processes • These processes are not independent of one another – E.g. attention may be part of perception; language may be part of memory and decision-making, etc.

Complexity of Cognition

Figure 1.1 (p. 3) - Complexity of Cognition

Sarah is walking toward her friend, who is waving in the distance. She is aware of her friend, but has little awareness of the stranger who is passing on her right, even though he is much closer.

What we are aware of… The complexities of cognition are usually hidden from our consciousness.

The Magic of Cognition

• In our lives we are likely to NEVER encounter the same retinal input twice!

EVER!

– We will learn about categorization and invariant representation

The Magic of Cognition

• The Stroop effect – We have automatic reading routines – It is hard to stop well-practiced routines from executing – This is the difference between experts and novices QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture.

Complexity of Perception; Expectations Figure 1.5 (p 8) Hemholtz’s unconcious inference

The display in (a) looks like (b) a gray rectangle in front of a light triangle; but it could be (c) a gray rectangle and a six-sided figure that are lined up appropriately.

Complexity of Perception; Expectations

QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture.

The Herring illusion

The diagonal lines give the impression of moving forward - the lines look like

optic streaks

(streaks of neural activation in the retina) When moving forward, straight lines (like doorways) start looking like curves on the retina.

The Magic of Cognition

• These types of phenomena give us a hint as to how cognition works – E.g. Do you process all of the information that falls on your retina?

• It may be that we have a perfect representation of the world • • It may be that we make gross estimations based on prior experience

DEMO

Complexity of Cognition

The “understand-the-brain” jigsaw puzzle is particularly daunting… To get a sense of the difficulty, imagine a jigsaw puzzle with several thousand pieces. Many of the pieces can be interpreted multiple ways, as if each had an image on both sides but only one of them is the right one. All the pieces are poorly shaped so you can’t be certain if two pieces fit together or not. Many of them will not be used in the ultimate solution, but you don’t know which ones or how many. Every month new pieces arrive in the mail. Some of these new pieces replace older ones, as if the puzzlemaker was saying, “I know you’ve been working with these old puzzle pieces for a few years, but they turned out to be wrong. Sorry. Use these new ones instead until future notice.” Unfortunately, you have no idea what the end result will look like; worse, you may have some ideas, but they are wrong.

- Jeff Hawkins,

On Intelligence

Methodology

How CogPsych is studied

• Donders reaction time experiment

Figure 1.3 (p. 6)

A modern version of Donders’ (1868) reaction time experiment. (a) the simple reaction-time task; and (b) the choice reaction-time task. For the simple time reaction text, the participant pushes the J key when the light goes on. For the choice reaction time test the participant pushes the J key if the left light goes on, and the K key if the right light goes on. The purpose of the Donders experiment was to determine the time it took to decide which key to press for the choice reaction time test.

Figure 1.4 (p. 7)

Sequence of events between presentation of the stimulus and the behavioral response, in Donders’ experiment. The dashed line indicates that Donders measured reaction time, the time between presentation of the light and the participant’s response. (a) simple reaction-time task; (b) choice reaction-time task.

How CogPsych is studied

• Behavioral and physiological

Figure 1.9 (p. 15)

Updated sequence of events between stimulus and response, taking into account the physio logical response. A, B, & C show relationships that can be measured. The mental response must be inferred from these relationships. Correction: Stimulus Physical/Mental Response Response E.g. Think back to the “mind=Windows” metaphor.

Figure 1.10 (p. 16)

Design of Davachi et al. (2003) experiment. There were two parts to this experiment. The first part, learning, was followed one day later by a memory experiment. Note that the participants’ brain activity was measured during the learning task using a technique called functional magnetic resonance imaging.

Figure 1.11 (p. 17)

Results for the behavioral part of the Davachi et al. (2003) experiment. This graph indicates the relationship between how the participants related to the stimulus (place or read) during learning and their performance in the memory test. This corresponds to Relationship A in Figure 1.9.

Figure 1.12 (p. 18)

The results of the physiological part of the Davachi et al. experiment. Left: The relationship between how the participants reacted to the stimulus during learning (place or read) and the physiological response (Relationship B). Right: The relationship between the physiological response and the behavioral response (whether the person recognized or forgot the word) (Relationship C).

Information Processing Approach

• Mind as a processor of information – Input -> Mental Processes -> Output • To understand it, build it Task I O Mind

Think Critically

Think Critically

• Beware cognitive myths – We only use 10% of our brain – Group brainstorming – Left vs right hemisphere • Left is an accountant, right is a hippie – Phrenology QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture.

Think Critically

• Beware vacuous Statements – E.g. (p. 4) “the Stroop effect shows that some stimuli can affect our behavior by

forcing themselves on our consciousness

, even if we are actively trying to ignore them.”

Think Critically

• Beware old theories – E.g. Chomsky’s

Poverty of Stimulus

argument (p. 10) has been rebuked recently; Perfors, Tenenbaum, & Regier (2006) have shown that with the right approach it is possible to retrieve grammar rules from the data available to children

Think Critically

• Correlation does not imply causation – 100% of people who eat pickles die – Therefore, eating pickles is bad for you

Think Critically

• “Davachi … [states that] memory is better if the perirhinal cortex is activated when the word is being learned” (p. 18) • Does this mean that Perirhinal cortex is involved in memory?

– Everything is involved in memory • Is it involved in associative learning?

– Not necessarily. It could be activated during the “place” task for any number of reasons » Maybe Ss found it amusing to place words, and the perirhinal cortex is actually the amusement center; maybe being amused correlates with better memory

Think Critically

• Cognition is far from being solved – Ask questions – Use your intuition – Do thought experiments – Use multiple sources of information – Think for yourselves • How would you design the mind?

On the brighter side…

• This is a young field, but we understand a lot about cognition already • At this point we are already able to predict – Learning curves for procedural and declarative memories – How forgetting works (interference and decay) – How some memories can prime other memories – How cognitive mechanisms interact – And much much more

Questions

Next Lecture

• Cognitive Architectures – Designing the mind • No homework