Method: Reaction Time (RT) Example: Simple detection ($, ruler, glasses) Liberal vs. conservative response criterion (speed/accuracy trade-off) Secondary task Additive method (e.g., visual degradation)

Subtractive Method Task 1: simple detection task press key when light blue appears on the screen Task 2: discrimination task Respond to the blue light but not to the yellow light The two tasks have: Same stimulus (blue light) Same response (key press) Only one thing different (?): discrimination vs. detection RT discrimination - RT detection = the mental operation of having to discriminate two stimuli

Subtractive Method Very simple and powerful method Developed by Donders in the 1800’s Used even today (e.g., fMRI studies) But it has its problems What constitute the elemental mental operation It is not very flexible

Additive Factors Method Developed by Sternberg (1969) Example: memory task (as already described) Numbers were displayed 3 9 5 4 Delay A probe 4 ‘yes’ Number of items in each trial vary from 1 to 6 items

3 7 9 2

9

Another trial

5 1

1

Plot: - RT relative to number of items in the list - plot separately ‘yes’ and ‘no’ trials

Stages: Encode target Search in WM Select response Start response INPUT OUTPUT Factors target visibility number of items target probability ease of response Example: Parkinson’s disease

Additive factors Assumes serial processing of stages Often this is not the case E.g., addition RT to decide 4 + 3 = 12 ‘no’ RT to decide 4 + 3 = 11 ‘no’ Because addition and multiplication are run in parallel But, does this mean a single system?

On Method: Dual task Tasks that tap onto the same system interfere with each other Having your room-mate talk to you when you are trying to remember a phone number (phonological code) No interference = independent systems

One STM ….. Or many? STM STM STM STM . . .

+ 3 9 8 2 1 7 4 Example: Short-Term Memory for Visual and Verbal Materials: One or two stores? Approach 1: Store maximum capacity of one type -- then see if person can remember any of the other type. Example: + Okay, here goes our experiment…. Take out a piece of paper (or write in the corner of your notes) I’ll present 2 things, first a string of numbers…then one of these objects. You try to remember both items as accurately as you can. Then I’ll present a second object, and you just write down “Y” if it’s the same as the one you were remembering, or “N” if it’s different. Next, you’ll see a red question mark…At this point write down the numbers you were remembering. (no looking at your neighbor’s answers!!) ready?? 3 9 8 2 1 7 4

4 9 3 2 6 8 7

?

One more time...

7 4 1 2 3 9 8

?

How did you do??

Usual Finding: ZERO interference between verbal and visual STM loads

- different memory systems are involved in the short term retention of objects and verbal stimuli… - This result is difficult to interpret without reference to mental representations. - Thus, we infer the existence multiple memory buffers, (a type of mental representations)

Question for thought If your data shows interference, can you still rescue the idea of independence between visual and verbal short-term memory? hint: itemize step-by-step what you did, making sure to not skip any steps (think of it as a writing computer code for a a machine to compute the task, do not make any pragmatic assumptions of knowledge).

Mental Representations: 3 Levels of Analysis (1) Computational: What is the problem to be solved? (i.e. input/output mapping of the mental process) (2) Algorithmic: How is this calculation carried out? (3) Implementational: What is the hardware that makes these calculations possible? example: (1)computational: a program that alphabetizes a list of names (2) algorithmic: by using a bubble sort procedure…sorting each name relative to all that come before it until all names have been sorted… (3) implementational: Pentium II processor and 4 gig hard drive... At the outset of the cognitive revolution, there was a real emphasis on the “sufficiency”of an algorithmic and computational level of description. Cognitive psychologists liked to argue that the implementation was essentially irrelevant to the worthy goal oftrying to understand the “essence” of how human thought processes operated. This goal remains the same, but recent advances in our understanding of the brain, and our ability to observe brain events have led to the conclusion that information about implementation can be a valuable tool in our search attempts to understand the computational and algorithmic levels of description….

Question for debate Does neuroscience (level 3) help for understanding psychology (i.e., how mental processes are carried out in level 2)? Yes: Reductionism; eliminativism cognitive neuroscience, No: functionalism, Marr (think birds and planes) dualism

Cognitive Psychology: The study of the structures, and processes of the mind and brain that take in, transform, and use information. But what do we mean by “information?” Today we’ll concentrate on unpacking this definition…talking about what we mean by “information” and “process” and also discussing some concrete examples of how these concepts are investigated through experimentation.

(Mental Representations) Types of Information (Mental Representations) Sensory information: - Images on our sensory organs, coming from light of a particular frequency that stimulates the rods and cones in our retinas Conscious Perception: that are stored in and manipulated by our minds (e.g., of color, sound, etc.) Sensory information is the “raw” form in which information from the environment begins in the brain, and perceptual apparatus. Representations begin when that “raw” information is transformed for further processing in the brain.

The distinction between what we perceive and the raw sensory information that first enters the brain is made clear by visual illusions like the ones I showed you last lecture…. Here’s another one…these two monsters probably appear to be different sizes at first glance (explaining first of all, why one monster is running AWAY from the other). But if you look carefully, you can see that the images themselves are exactly identical. Our visual system transforms our perceptions of size based on the environmental cues present in the picture.

Other types of mental representation (memories): Procedural knowledge (“knowing how”): e.g. how to throw a frisbee, swing a golf club, drive a car…In other words, skill knowledge, or knowledge that doesn’t refer to the state of things in the world. Declarative knowledge (“knowing that”): (1) Semantic knowledge (referred to as generic knowledge in your textbook) refers to facts about the world. E.g. what color is the sky?, what is 7x9?, who is the quarterback for the Ducks? These types of representation are probably more in line with what you would think of as “knowledge”. (stored information…information in memory) Procedural knowledge Declarative knowledge semantic episodic Are these truly different memory types? Or are they just different ways to describe the information in memory? The Procedural/Declarative distinction is supported by evidence from amnesic populations. Most amnesiac patients can still acquire procedural knowledge while remaining unable to acquire new declarative knowledge. So H.M. has been taught to do a simple pursuit-rotor task. Although he is now much better at the task than he was at the beginning, he has no memory of ever having learned the task. The episodic/semantic distinction is more tenuous…some evidence in favor some that doesn’t support it….nevertheless, it is an interesting and useful theoretical distinction. (2) Episodic knowledge: knowledge about the world that is specific to a particular time and place. E.g. What’s the last song you heard on the radio? What time did you wake up this morning? Where were you last New Year’s Eve?

Cognitive Psychology: The study of the structures, and processes of the mind and brain that take in, transform, and use information. But what do we mean by “processes?”