BA and RFT Flashcards
___________: A decrease in the intensity or probability of a reflex response resulting from repeated exposure to a stimulus that elicits that response
Habituation
___________: A relationship between a specific event and a simple- involuntary response to that event
Reflex (Chance, 2014: 33)
Modal action pattern: A series of interrelated acts found in all or nearly all members of a ___________:
Species
___________: An increase in the intensity or probability of a reflex response resulting from earlier exposure to a stimulus that elicits that response
Sensitization
___________: Any event that affects- or is capable of affecting- behavior
Stimulus (Chance, 2014: 24)
___________: Any stimulus that reliably elicits a fixed action pattern
Releasing stimulus
Releasing stimulus: Any stimulus that reliably ___________ a fixed action pattern
elicits
___________: Actions of the whole organism that can be measured
Behavior
___________: the development or evolutionary history of a species
Phylogeny
Phylogeny: the development or evolutionary history of a ________
species
___________: development or life history of an individual organism
Ontogeny
Ontogeny: development or life history of an ___________
organism
___________: Any stimulus the removal of which is reinforcing; characterizing an event that is likely to be avoided
Aversive
Aversive: Any stimulus the ___________ of which is reinforcing; characterizing an event that is likely to be avoided
removal
_________ stimulus: Any stimulus the presence of which is reinforcing
Appetitive
___________: A graphic record of behavior- each point of which reflects the total number of times a behavior has been performed as of that time
Cumulative record
___________: time-series research design with repeated baseline and intervention conditions
ABAB
ABAB design: time-series research design with ___________ baseline and intervention conditions
repeated
___________: Time-series research design in which two or more interventions alternate systematically
ATD
alternating-treatments design: Time-series research design in which two or more interventions ___________
alternate systematically
___________: time-series research design that involves successively changing the criterion for delivering consequences
changing criterion
changing criterion design: time-series research design that involves successively changing the criterion for ___________
delivering consequences
___________: research design with repeated treatments across different situations
multiple-baseline
___________: An experimental design in which the independent variable is made to vary across two or more groups of subjects
Between-subjects experiment
___________: period of observation but no intervention
baseline
Pavlovian Extinction: the procedure of repeatedly presenting a CS without the ___________
US (unconditioned stimulus)
Pavlovian ___________: the procedure of repeatedly presenting a CS without the US
Extinction
Operant Extinction: the procedure of ___________ the reinforcers that maintain a behavior
withholding
Operant ___________: the procedure of withholding the reinforcers that maintain a behavior
Extinction
___________: events dependent on the appearance of a stimulus
Stimulus contingent
___________: events dependent on the appearance of a behavior
Response contingent
___________ conditioning: A Pavlovian conditioning procedure in which the CS and US occur together in time
Simultaneous
___________ conditioning: A Pavlovian conditioning procedure in which the CS begins and ends before the US is presented
Trace
___________ conditioning: A Pavlovian conditioning procedure in which the CS starts before- and then overlaps with- the US
Delayed
___________ conditioning: A Pavlovian conditioning procedure in which the US precedes the CS
Backward
___________: A variation of Pavlovian conditioning in which a stimulus is paired- not with a US- but with a well-established CS
Higher-order
___________: Failure of a stimulus that is part of a compound stimulus to become a CS
Overshadowing
___________: Failure of a stimulus to become a CS when it is part of a compound stimulus that includes an effective CS
Blocking
___________: In Pavlovian discrimination training- the stimulus that is regularly paired with a US
CS+
___________: In Pavlovian discrimination training- the stimulus that regularly appears in the absence of the US
CS-
Contiguity: ___________ of events in time (temporal contiguity) or space (spatial contiguity)
nearness
___________: The interval between the CS and US
Interstimulus interval (ISI)
___________: The interval separating the trials of a discrete trial procedure
Intertrial interval
Unconditional response: The response ___________ by an unconditional stimulus
elicited
___________: The response elicited by an unconditional stimulus
Unconditional response (UR)
___________: the response elicited by a conditional stimulus
Conditional response (CR)
Conditional response: the response elicited by a ___________ stimulus
conditional
___________: The stimulus that elicits a conditional response
Conditional stimulus (CS)
___________: The stimulus that elicits an unconditional response
Unconditional stimulus (US)
___________: The sudden reappearance of a behavior following its extinction
Spontaneous recovery
___________ therapy: A form of counterconditioning in which a CS is paired with an aversive US
Aversion
Systematic ___________: A form of counterconditioning for treating phobias in which a person imagines progressively stronger forms of the frightening CS while relaxed It
desensitization
___________: A reduction in the rate of responding due to the noncontingent presentation of an aversive CS
Conditioned suppression
___________ therapy: Any of several forms of counterconditioning in which a person is gradually exposed to a feared stimulus
Exposure
___________: The use of Pavlovian conditioning to reverse the unwanted effects of prior conditioning
Counterconditioning
___________ chaining: A procedure in which training begins with the first response in the chain and adds subsequent links in order
Forward
Forward chaining: A procedure in which training begins with the _____ response in the chain and adds subsequent links in order
first
___________ chaining: A procedure in which training begins with the last link in the chain and adds preceding links in reverse order
Backward
___________ learning: A form of negative reinforcement in which the subject first learns to escape- and then to avoid- an aversive
Escape-avoidance
Satiation: A ___________ in the effectiveness of a reinforcer due to exposure to or consumption of the reinforcer
reduction
___________: A reduction in the effectiveness of a reinforcer due to exposure to or consumption of the reinforcer
Satiation
___________ reinforcement: A procedure that increases behavior in which a behavior is followed by the presentation of- or an increase in the intensity of- a stimulus
Positive
___________ reinforcement: A procedure that increases behavior in which a behavior is followed by the removal of- or a decrease in the intensity of- a stimulus
Negative
Positive reinforcement: A procedure that increases behavior in which a behavior is followed by the ___________ of- or an increase in the intensity of- a stimulus
presentation
Negative reinforcement: A procedure that increases behavior in which a behavior is followed by the ___________ of- or a decrease in the intensity of- a stimulus
removal
___________: A sudden increase in the rate of behavior during the early stages of extinction
Extinction burst
Extinction burst: A sudden ___________ in the rate of behavior during the early stages of extinction
increase
___________: A neurotransmitter that is thought to be important in reinforcement More commonly known as adrenaline
Epinephrine
___________ procedure: A training procedure in which a behavior may be repeated any number of times
Free operant
___________ procedure: An operant training procedure in which performance of a behavior defines the end of a trial
Discrete trials
___________ learning: Any procedure in which a behavior becomes stronger or weaker (eg- more or less likely to occur)- depending on its consequences
Operant
___________ reinforcer: Any reinforcer that has acquired its reinforcing properties through its association with other reinforcers
Secondary
Secondary reinforcer: Any reinforcer that has ___________ its reinforcing properties through its association with other reinforcers
acquired
___________ reinforcer: Any reinforcer that is not dependent on another reinforcer for its reinforcing properties
Primary
___________ reinforcer: Any reinforcing event that follows automatically (naturally) from a behavior
Natural
___________ reinforcer: Any reinforcing event that has been arranged by someone- usually for the purpose of modifying behavior
Contrived
Contrived reinforcer: Any reinforcing event that has been ___________ by someone- usually for the purpose of modifying behavior
arranged
___________ operation: Anything that establishes conditions that improve the effectiveness of a reinforcer Also called establishing operation
Motivating
___________: In operant training- the procedure of establishing a behavior chain
Chaining
Shaping: In operant training- the procedure of reinforcing successive ___________of a desired behavior
approximations
___________: One of the brain’s major neurotransmitters that is thought to play an important role in reinforcement
Dopamine
___________: The essential elements of operant learning- often represented by the letters ABC
Three-term contingency
Premack principle: The observation that high-probability behavior ___________ low-probability behavior
reinforces
___________: The observation that high-probability behavior reinforces low-probability behavior
Premack principle
___________: The procedure of identifying the component elements of a behavior chain
Task analysis
___________: The procedure of providing consequences for a behavior that increase or maintain the strength of that behavior
Reinforcement
___________: The reappearance during extinction of a previously reinforced behavior
Resurgence
Resurgence: The ___________ during extinction of a previously reinforced behavior
reappearance
___________ schedule: A complex reinforcement schedule in which reinforcement is contingent on the behavior of two or more organisms
Cooperative
___________schedule: A complex reinforcement schedule in which two or more simple schedules alternate- with each schedule associated with a particular stimulus
Multiple
___________ schedule: A complex reinforcement schedule in which two or more simple schedules are available at the same time
Concurrent
___________ schedule: A complex reinforcement schedule in which two or more simple schedules- neither associated with a particular stimulus- alternate
Mixed
___________ schedule: A complex reinforcement schedule that consists of a series of simple schedules- each of which is associated with a particular stimulus- with reinforcement delivered only on completion of the last schedule in the series
Chain
___________ schedule: A complex reinforcement schedule that consists of a series of simple schedules (without particular stimuli)- with reinforcement delivered only on completion of the last schedule in the series
Tandem
___________: A form of differential reinforcement in which a behavior is reinforced only if it occurs at least a specified number of times in a given period
Differential reinforcement of high rate (DRH)
___________: A form of differential reinforcement in which a behavior is reinforced only if it occurs no more than a specified number of times in a given period
Differential reinforcement of low rate (DRL)
___________: A pause in responding following reinforcement; associated primarily with FI and FR schedules
Postreinforcement pause
___________: A reinforcement schedule in which a behavior is reinforced each time it occurs
Continuous reinforcement (CRF)
Continuous reinforcement: A reinforcement schedule in which a behavior is reinforced ____ it occurs
each time
___________ Schedule: A reinforcement schedule in which a behavior is reinforced the first time it occurs following a specified interval since the last reinforcement
Fixed interval (FI)
Fixed Interval Schedule: A reinforcement schedule in which a behavior is reinforced the first time it ___________ following a specified interval since the last reinforcement
occurs
___________ Schedule: A reinforcement schedule in which a behavior is reinforced the first time it occurs following an interval since the last reinforcement- with the interval varying around a specified average
Variable interval (VI)
Variable interval Schedule: A reinforcement schedule in which a behavior is reinforced the first time it occurs following an interval since the last reinforcement- with the interval ___________ around a specified average
varying
___________ Schedule: A reinforcement schedule in which reinforcement is contingent on the continuous performance of a behavior for a fixed period of time
Fixed duration
___________ Schedule: A reinforcement schedule in which reinforcement is contingent on the continuous performance of a behavior for a period of time- with the length of the time varying around an average
Variable duration (VD)
___________ Schedule: A reinforcement schedule in which reinforcement is delivered at varying intervals regardless of what the organism does
Variable time (VT)
___________ Schedule: A reinforcement schedule in which reinforcement is delivered independently of behavior at fixed intervals
Fixed time (FT)
___________ Schedule: A reinforcement schedule in which- on average- every nth performance of a behavior is reinforced
Variable ratio (VR)
___________: A rule describing the delivery of reinforcers for a behavior
Schedule of reinforcement
___________: Any operant training procedure in which certain kinds of behavior are systematically reinforced and others are not
Differential reinforcement
___________: Disruption of the pattern of responding due to stretching the ratio of reinforcement too abruptly or too far
Ratio strain
___________: The distinctive rate and pattern of responding associated with a particular reinforcement schedule
Schedule effects
Matching law: The principle that- given the opportunity to respond on two or more reinforcement schedules- the rate of responding on each schedule will ___________ the reinforcement available on each schedule
match
___________: The procedure of gradually increasing the number of responses required for reinforcement
Stretching the ratio
___________: The procedure of providing reinforcers independently of behavior
Noncontingent reinforcement (NCR)
The rate at which a behavior occurs once it has resumed following reinforcement
Run rate
___________: The tendency of a behavior to be more resistant to extinction following partial reinforcement than following continuous reinforcement
Partial reinforcement effect (PRE)
___________: A form of differential reinforcement in which a behavior that is incompatible with an unwanted behavior is systematically reinforced
Differential reinforcement of incompatible behavior (DRI)
___________: A form of differential reinforcement in which reinforcement is contingent on the complete absence of a behavior for a period of time
Differential reinforcement of zero responding (DR0)
___________ punishment: A procedure that reduces behavior in which that behavior is followed by the presentation of- or an increase in the intensity of- a stimulus Also called type 1 punishment
Positive
Positive punishment: A procedure that reduces behavior in which a behavior is followed by the ___________ of- or an increase in the intensity of- a stimulus Also called type 1 punishment
presentation
___________ punishment: A procedure that reduces behavior in which a behavior is followed by the removal of- or a decrease in the intensity of- a stimulus
negative
___________: Any consequence of a behavior that decreases the strength of that behavior
Punisher
___________: The procedure of altering the environment to prevent unwanted behavior from occurring
Response prevention
Punishment: The procedure of providing consequences for a behavior that ____ the strength of that behavior
decreases
___________: The procedure of providing consequences for a behavior that reduce the strength of that behavior
Punishment
___________: A self-control technique consisting of directing attention away from events that are likely to elicit undesirable behavior
Distraction
___________: A self-control technique consisting of doing something that physically prevents an undesirable behavior from occurring
Physical restraint
___________: A self-control technique consisting of keeping a tally of the number of times the behavior in question occurs
Monitoring behavior
___________: A self-control technique consisting of staying away from situations that are likely to elicit undesirable behavior
Distancing
___________: Any increase in the strength of behavior that is due to coincidental reinforcement
Superstitious behavior
___________: The failure to escape an aversive following exposure to an inescapable aversive
Learned helplessness
___________ punishment: A decrease in an observer’s tendency to imitate a model when the model’s behavior has been punished
Vicarious
vicarious ___________: An increase in an observer’s tendency to imitate a model when the model’s behavior has been reinforced
reinforcement
___________: Any procedure in which an organism learns by observing the behavior of another organism
Observational learning
Generalized imitation: The tendency to imitate modeled behavior even though the imitative behavior is not ___________
reinforced
___________: The tendency to imitate modeled behavior even though the imitative behavior is not reinforced
Generalized imitation
___________ discrimination training: A discrimination training procedure in which the S+ and S- are presented at the same time
Simultaneous
___________ discrimination training: A discrimination training procedure in which the S+ and S- are presented one after the other in random sequence
Successive
___________: A discrimination training procedure in which the task is to select from two or more comparison stimuli the one that matches A sample
Matching to sample (MTS)
___________: A stimulus in the presence of which a behavior will be reinforced
SD (S+)
S?: A stimulus in the presence of which a behavior ___________ be reinforced
will not
___________: A stimulus in the presence of which a behavior will not be reinforced
S? (S-)
___________: Any procedure for establishing a discrimination
Discrimination training
___________: In operant discrimination training- any stimulus that signals either that a behavior will be reinforced (an S+ or SD) or will not be reinforced (an S- or S?)
Discriminative stimulus
___________: A generalization gradient showing an increased tendency to respond to the S+ or CS+ and stimuli resembling them
Excitatory gradient
___________: A gradient showing a decreased tendency to respond to the S or CS and stimuli resembling them
Inhibitory gradient
___________: The finding that discrimination training proceeds more rapidly when different behaviors produce different reinforcers
Differential outcomes effect (DOE)
___________: The tendency following discrimination training for the peak of responding in a generalization gradient to shift away from the CS or S
Peak shift
___________: The tendency for a behavior to occur in the presence of certain stimuli but not in their absence
Discrimination
___________: The tendency for a learned behavior to occur in the presence of stimuli that were not present during training
Generalization
___________ method: A method of measuring forgetting by comparing the rate of extinction after a retention interval with the rate of extinction immediately after training
Extinction
___________ method: A method of measuring forgetting in which a behavior is learned to criterion before and after a retention interval
Relearning (savings)
___________: A method of measuring forgetting in which a behavior is tested for generalization before and after a retention interval - A flattening of the generalization gradient indicates forgetting
Gradient degradation
___________: A method of measuring forgetting in which hints (prompts) about the behavior to be performed are provided
Prompted (cued)
___________ recall: A method of measuring forgetting in which the subject is required to identify stimuli experienced earlier
Recognition
___________ recall: A method of measuring forgetting that consists of providing the opportunity to perform the learned behavior
Free
___________ forgetting: Forgetting that results from the absence of cues that were present during training
Cue-dependent
___________ learning: Learning that occurs during a particular physiological state (such as alcoholic intoxication) and is lost when that physiological state passes
State-dependent
___________: Number of correct responses per minute In general- a fluent performance is smooth- accurate- and relatively rapid
Fluency
___________: The continuation of training beyond the point required to produce one errorless performance
Overlearning
Retention interval: The time between training and testing for ____
forgetting
Continuum of ___________: The idea that organisms are genetically disposed to learn some things and not others
preparedness
Behavior analysis
the science of behavior change
Behavior analysis
the study of the functional relations between behavior and environmental events
Functional relation
the tendency of one event to vary in a regular way with one or more other events
behavior
anything a person does that can be observed
overt behavior
behavior that can be observed by someone other than the person performing it
covert behavior
behavior that can be observed only by the person performing it
respondent behavior
behavior that is most readily influenced by events that precede it; reflexive behavior
operant behavior
behavior that is readily influenced by events that follow it.
behavior repertoire
all the things an individula is capable of doing at any given moment
antecedents
environmental events that occur before a behavior
consequences
environmental events that occur after a behavior
environmental event
any event in a person’s environment that can be observed
learning history
all the environmental events (antecedents and consequences) that have affected a person’s behaivor upt o the present
applied behavior analysis
the attempt to solve behavior problems by providing antecedents and/or consequences that change behavior
medical model
the view that behavior problems are merely symptoms of an underlying psychological disorder
symptom substitution
the idea that if a beahvior problem is solved without resolving the underlying psychological disorder- another behavior problem will take its place
behavioral assessment
the attemp to (1) define the target behavior; (2) identify functional relations between the target behavior and its antecedents and consequences; and (3) identify an effective intervention for changing the target behavior.
target behavior
the behavior to be change by an intervention
functional analysis
the process of testing hypothese about the functional relations among antecedents- target behavior- and consequences
continuous recording
recording each and every occurrence of a behavior during a prescribed period.
interval recording
recording whether a behavior occurs during each of a series of short intervals within an observation period
single case experimental design
a research design in which the behaivor of an individual is compared under experimental and control conditions
baseline
a period during which the behavior under study is recorded- but no attempt is made to modify it
ABAB reversal design
a sincle case design in which baseline and intervention conditions are repeated with the same person
multiple baseline design
a single case design in which the effects of an intervention are recorded across situations- behavior- or individuals
alternating treatments design
a single case experimental design in which two or more interventions alternate systematically
law of effect
in any given situation- the probability of a behavior occurring is a function of the consequences that behavior has had in that situation in the past
reinforcer
an event that- when made contingent on a behavior- increases or maintains the frequency of that behavior
positive reinforcer
a reinforcing event in which something is added following a behavior
negative reinforcer
a reinforcing event in which something is removed following a behavior
primary reinforcers
reinforcers that are not dependent on their association with other reinforcers
secondary reinforcers
reinforcers that are dependent on their association with other reinforcers
contrived reinforcers
reinforcers that have been arranged by someone for the purpose of modifying behavior
natural reinforcers
reinforcers that have not been arranged by someone for the purpose of modifying behavior; spontaneous or unplanned reinforcers
bootleg reinforcement
reinforcement that is not part of- and tends to undermine- an intervention
behavioral contrast
the tendency for a reinforced behavior to occur less often in situations in which it has not been reinforced
prompt
an antecedent that induces a person to perform a behavior that otherwise does not occur
prompting
the procedure of providing antecedents that evoke a target behavior
fading
gradually reducing the strength of a prompt
shaping
the reinforcement of successive approximations of a target behavior
behavior chain
a sequence of related behaviors- each of which provides the cue for the next- and the last of which produces a reinfrocer
chaining
the reinforcement of successive elements of a behavior chain
forward chaining
a chaining procedure that begins with the first element in the chain and progresses to the last element
backward chaining
a chaining procedure that begins with the last element in the chain and progresses to the first element
extinction
withholding the reinforcers that maintain a target behavior
partial reinforcement effect
increased resistance to extinction following intermittent reinforcement
extinction burst
a sharp increase in the frequency of the behavior on extinction
resurgence
the reappearance- during extinction- of previously effective behavior
spontaneous recovery
the reappearance of the target behavior following its extinction
differential reinforcement
any procedure that combines extinction and reinforcement to change the frequency of a target behavior
DRL
the procedure of reinforcing the target behavior only when it occurs at a low rate
DRA
the procedure of reinforcing an alternative behavior instead of the target behavior
DRI
the procedure of reinforcing a behavior that is incompatible with the target behavior
A punisher is an event that- ________
… when made contingent on a behavior- decreases the frequency of that behavior
Punishment is the procedure of ____________
… providing consequences for a behavior that decrease the frequency of that behavior
reprimand
to reduce the frequency of a target behavior by making disapproval contingent on the target behavior
response cost
to reduce the frequency of a target behaivor by making removal of a reinforcer contingent on the target behavior (e.g. parking ticket)
time out
to reduce the frequency of a target behavior by making removal of a person from a reinforcing situation contingent on the target behaivor
- Monitor ________________
- [Decide if punishment is really necessary or if reinforcement might work.]
law of effect
In any given situation- the probability of a behavior occurring is a function of the consequences that behavior has had in that situation in the past.
An example of negative reinforcement would be:
Engaging in distracting activities to avoid having a disagreeable discussion with your wife (note this could also be seen as positive punishment but emphasis here is on increased frequency of avoidance behaviours).
Some disadvantages of punishment include:
The person administering the punishment can become a conditioned punisher-
In popular language- “punishment” is usually thought of as ____________
retribution
The tendency for behavior to occur more frequently in one situation than another is called _____________
stimulus discrimination. (NB this is why discrimination is at the heart of learning- it is not just about changing frequency of behaviour- it is about applying it appropriately in context).
Stimulus discrimination is ______________
the tendency for behavior to occur more frequently in one situation than another.
An example of stimulus discrimination is ________________
dressing appropriately for the context-
A discriminative stimulus is ________________
Any event in the presence of which a target behaviour is likely to have consequences that affect its frequency.
An S^D is ____________
An event in the presence of which the target behaviour is reinforced.
An Sdelta is ____________
An event in the presence of which the target behaviour is NOT reinforced.
Sdeltas are correlated with ______________ or ______________
extinction or punishment.
S^Ds are correlated with _____________
reinforcement
Discrimination training is ______________
any procedure that results in a target behaviour having different frequencies in different situations.
Discrimination training usually involves _______________
reinforcing in the presence of S^D’s and not reinforcing or punishing in the presence of Sdeltas
An example of simultaneous discrimination training would be ___________
match to sample
An example of successive discrimination training would be _____________
noting practice in meditation training
Errorless discrimination training involves ______________
presenting Sdeltas in very weak form and then increasing their strength.
An example of errorless discrimination training in the workplace would be _____________
Doing a series of role plays of increasing difficulty
Modal action patterns differ from reflexes in that they involve the _____________organism and are more _____________and _____________ (Chance- 2013)
entire- complex- variable
Modal action patterns are _____________ by events called _____________ (Chance- 2013)
elicited- releasers
General behaviour traits have a strong _____________ component but occur in _____________ situations (Chance- 2013)
genetic- many
Natural selection produces three categories of behaviour: _____________ - _____________ and _____________ (Chance- 2013)
reflexes- modal action patterns and general behaviour traits
An FR20 schedule of key pressing would mean the subject received a reinforcer …
every 20 times they pressed the key
Dougher, Auguston et al. (1994) demonstrated that
… people could come to fear (measured by skin conductance) stimuli in an equivalence class with a CS+ associated with shock. In study 2, they showed that extinction training on the CS+ also transferred to members of the equivalence class.
Human beings were naturally selected for a preference for ____________ and ___________ and due to a change in the environment, these preferences now lead to diseases.
sugar and salt. (Chance, 2014) NB this is a nice demonstration of the problem with natural selection is that it is slow.
learning can be defined as…. (Chance, 2014:21)
a change in behaviour due to experience. (NB it cannot be defined as a change in the brain because we cannot tell what is learned from looking at brain, behaviour is a different level. Also taking a drug or being hit on the head would fit this definition but is not learning).
Learning involves a change in an aspect of behaviour such as its … (Chance, 2014: 21)
frequency, intensity, speed or form
One piece of evidence that thinking is covert speech is…
brain damage or temporary disruption of speech centers impairs self speech
Stimuli are ____________ changes in the organisms environment (Chance, 2014: 24) .
physical (NB what is the status of a thought as a stimulus for action?)
Habituation has survival value because …
events that occur repeatedly and do not signal danger or opportunity can distract us from more important things.
A natural science approach to behaviour assumes that a) _______, b) _______, c) _______ (Chance, 2014: 36)
a) all natural phenomena are caused,
b) causes precede effects (e.g. not study hard because will get a good grade).
c) causes are themselves natural phenomena (not mental constructs)
c) the simplest explanation is the best (law of parsimony).