CHAPTER 1: INTRODUCTION
1.1 - What Is Cognition?
Folk Psychology: A set of assumptions and theories based on everyday behaviours of
ourselves and others.
o Scientific psychology seeks to refine this common sense folk psychology.
Cognitive concepts: awareness, intelligence, intuition, personal acquaintance,
recognition, skill, and understanding.
The subject matter of cognitive psychology is information-processing. This includes
things like attending, comprehending, remembering, and problem-solving.
o This info-processing concept came from research on telephone & radio
o The research showed that communication can be broken into a sequence of events
with at least 3 major stages:
Sender, communication channel, and receiver.
1.2 – Cognitive Psychology & Information Theory
Information Theory: The information provided by a particular event is inversely related
to its probability of occurrence.
o Information reduces uncertainty for the receiver.
o Less probable = more informative.
Bit: Short for ‘binary digit’ – an event that occurs in a situation with 2 equally likely
outcomes provides one ‘bit’ of information.
o If you have to guess a number, then the number of bits corresponds to the number
of questions you would need to ask to reach the right answer.
1.3 – Early Tests of Information Theory
People respond more slowly to less likely signals.
Experiment: there are 10 buttons, 1 for each finger.
o Participants were informed in advance which stimuli were possible.
o The number of possible signals ranged from 1 to 10.
o As the number of alternatives increased from 1 to 10, so did response time.
When the number of possible stimuli is small, there’s little uncertainty as to which signal
o Therefore, the information produced by a stimulus is small.
o Response time (RT) increases with the number of possible stimulus alternatives.
Sequential dependencies experiment (Hyman) o In a situation with 2 alternatives, the probability of change from 1 alternative to
the other on trial ‘n’ to trial ’n+1’ was 0.80.
o Thus, the probability of repeating the same signal on successive trials was 0.20.
o RT became faster as a signal’s probability increased.
o RT became slower as a signal’s probability decreased.
1.4 – Information-Processing Limitations
o Amount of time it takes for information to flow through the nervous system (NS).
o Amount of visual information that a person can transmit at once.
Control tower experiment:
o Control tower operators received simultaneous messages.
o The messages were either of an airplane’s call signals or of 3 unrelated words.
o There are 10 possible call signals and there are over 1000 possible words to be
used for the second message.
o Results: the operators could identify the call signals from 2 airplanes
simultaneously but they could identify only one of two simultaneous word
When two messages arrive simultaneously, the amount of interference between them
depends on the amount of info they convey.
Two tasks with low information value can be carried out simultaneously without
Broadbent: the limit is one of information rather than stimulation.
o For an example, Broadbent found that the disrupting effect of a buzzer on
understanding a verbal message was increased if a person thought that other
messages might also arrive, although they didn’t.
We deal with lots of information by selecting only some of the total available info,
particularly info that shares some basic physical property, such as arriving in a particular
voice or from a certain location.
1.5 – Models of Information-Processing
Broadbent’s Filter Model
o Filter Model: Based on the idea that info-processing is restricted by channel