Applied Research Methods: Brain & Cognition
Lecture 1
Introduction
Overview of the different methods plotted with on the Y-axis
the spatial resolution and on the X-axis the temporal
resolution. Typically, there is a trade of between methods that
have a good spatial resolution and methods that have a good
temporal resolution. There is a difference in cost between the
methods, some methods depend on lesions, and some are only
possible in animals (invasive).
▪ Temporal resolution: the accuracy with which one can measure an
event is occurring.
▪ Spatial resolution: the accuracy with which one can measure where
an event is occurring.
▪ Invasiveness: whether or not the equipment is located internally or
externally.
Good temporal resolution > EEG/ERP, MEG, TMS, and single-cell recordings.
Bad temporal resolution > PET and fMRI.
Good spatial resolution > lesion studies, single-cell recordings, and fMRI.
Some measures can only measure a correlation. To measure a causal relation, a region in the brain has to be disrupted
(interference) which can be done via TMS of microsimulation.
Performance-based measures: response times (i.e., changes in nature or efficiency of information processing manifests
in the time it takes to complete a task) and accuracy rates (i.e., error rates, percentage correct, or percentile
performance).
▪ Advantages: reflect real behavior and simple to analyze and interpret.
▪ Disadvantages: hard to link directly to neural substrates.
Mental chronometry: the study of the time-course of information processing in the human nervous system.
In this lecture the methods are explained with face perception: a single face can produce radically different images on
our retina when it changes expression and/or orientation.
Importance of faces:
▪ Central role in human interactions.
▪ Contribute to speech perception.
, ▪ Communicate a wealth of social information: such as physical structure (e.g., age, gender, and personal
identity), facial expression (e.g., mood and emotional state), and direction of tgaze (e.g., interest/attentional
focus).
Faces as visual stimuli:
▪ Faces as a category highly homogenous (similar): share basic component parts in a fixed configuration (two
eyes over a nose over a mouth inside an ellipse).
▪ Individual faces are highly different: vary in many dimensions, including head shape, individual features,
relative feature placement, color, texture, etc.
▪ Faces are dynamic and changeable due to movable parts that change shape and relative position: for example,
a smile versus an angry frown, but it stays the same face.
Processing of faces is configural/holistic: generally, object recognition is considered to operate via feature recognition
– in other words, recognition of objects is based on the shape of its parts.
Faces however all share the same features. One solution could involve recognizing the relations between the parts of
the face rather than the parts.
▪ Configurational: computation of the spatial configuration of the components.
▪ Holistic: integration over whole face.
Objects have no face-like features at itself but putting them together in a face-like shape, then we can recognize it as a
face.
Inverted faces: provide an ideal case because they are identical in terms of within-class similarity, complexity, and
features. Via inverted faces researched have tested holistic processing (how inverted faces have an impact on face
recognition).
Thatcher illusion: phenomenon where it becomes more difficult to detect local feature
changes in an upside-down face, despite identical changes being obviolus in an upright
face. The Thatcher illusion demonstrates that the brain does not merely process and store
representations of whole faces, but it recognizes isolated facial features such as the
mouth and eys. So, faces are processed differently when they are inverted, and the brain
is sensitive to upright faces and not so much to upside-down faces.
Yin (1969): Yin initiated the face recognition debate with his studies of the
effects of inversion on the recognition of faces versus other types of
objects. Stimuli were unfamiliar faces, airplanes, and houses – all typically
seen only in an upright orientation. The stimuli were presented in an
old/new memory paradigm, firstly they were presented with a set of target
stimuli, after a delay they were tested with target sitmuli and distractors
and they had to indicate whether the stimuli was parts of the target stimuli
they had previously memorized.
,The results show a face inversion effect. For the houses and planes they were slightly worse for the inverted stimuli
compared to the upright stimuli, but for faces this difference in error rate was much larger. This provides evidence that
we process faces differently from other objects.
▪ Face inversion effect: faces show a disproportionate effect of inversion. This persists even when upright
performance is equated.
Bayliss & Tipper (2005): behavior that is associated with faces is gaze cuing. In this study the researches were
interested in wheter we move our attention in the direction of the gaze of an individual.
On the first screen both women look at the man in the middle. After some time the man directs his gaze towards the
woman on the right, and after some more time the women on the right is shown in color. The participant has to press a
button whenever he/she sees the colored face (reaction time).The idea is that if you follow the gaze of the central
person, you are faster to detect the colored face when this is cued, as compared to the uncued face.
Another condition in this study is done with scrambled faces. So, the difference is that in the first condition it is a
social gaze, and in this condition it is not.
The researchers were interested in these types of effect depend on how high
someone scores on the Autism-Sepctrum Quotient questionnarie.
The difference in RT benefit between the invalid and valid, is larger in the low AQ
group compared to the low AQ group. This suggests a link between a personality
trait of AQ and the degree that you are cued in a social situation.
There is evidence for specialized processing of social stimuli.
Newborns are able to detect faces.
A study was done in neonatal face recognition (in newborns with a median age of
9 minutes). A bord was shown with on the bord elements that were arranged in a
face-like matter or in a scrambled manner (schematic faces). The researcher moved
the bords across the face from left to right and they measured how long the baby’s
tracked the bords. Faces are tracked for longer than scrambled or black faces. This
suggest that there in an innate processing mechanism for detecting faces.
, Preferential looking paradigm: an infant is presented with a number of stimuli and the amount of time that the infant
spends looking at each of the stimuli is scored. A deviation from change implies that the infant is able to discriminate
between the two stimuli and has a preference for one.
Habituation paradigms: the same stimulus is presented repeatedly and the infant’s attention toward the stimulus
(looking time) diminished. The attention increases when a new stimulus is presented, which implies that the infant
recognizes that the stimulus is different.
Observational measures: code “what” is being done or “how often” something is done through one person observing
the behavior of others.
▪ Advantages: can be used when it is impossible or inappropriate to give instructions and can be used in
naturalistic settings.
▪ Disadvantages: difficulties associated with scoring behavior and observer bias (inter-rater reliability).
Measuring unconsciousness: subliminal perception (influence behavior in the absence of conscious report) >
presenting a visual stimulus unconsciously for a brief duration and follow it with junk visual material (masking),
which prevents an after image. To know whether something was unconscious > verbal report or wagering.
Survey methods: questioning a participant using questions and a set of responses that are fixed in advance or questions
and a range of responses that are open-ended.
Reliability > different formulation of the same question or ask the same question on a different time-point.
External validity > improved by administering surveys anonymously and confidentially.
▪ Advantages: can be used when an experimental manipulation is not possible or unethical; they measure
thoughts and beliefs.
▪ Disadvantages: may not reflect the true behavior; social cognition may occur unconsciously.
Bodily responses: for example, skin conductance response > increased activity in the sympathetic system is commonly
measured by monitoring small changes in conductivity as a result of mild sweating.
▪ A weak electrical current is applied to the skin in order to measure the skin conductance response (SCR) or
galvanic skin response (GSR).
Electromyography (EMG): measure of electrical activity association with muscle contraction, and thus the increase in
action potentials; the greater the force produced by the muscles, the greater the electrical activity > is also used to
measure the eyeblink startle response > needs a baseline measure (because of fluctuations).
▪ Advantages: present in the absent of awareness of a stimulus or specific task, easy to record and analyze.
▪ Disadvantage: not straightforward to link bodily reponses to brain and behavior.
Electrophysiological methods: measuring changes in the responsiveness of a neuron to changes in a stimulus or
changes in a task, one can make inferences about the building blocks of cognitive processing.
Single-cell recordings: implanting very small electrodes either in an axon or outside the membrane and measuring the
number of times an action potential is produced > rate coding and temporal coding.
