Interstimulus interval

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The interstimulus interval (often abbreviated as ISI) is the temporal interval between the offset of one stimulus to the onset of another. For instance, Max Wertheimer did experiments with two stationary, flashing lights that at some interstimulus intervals appeared to the subject as moving instead of stationary. In these experiments, the interstimulus interval is simply the time between the two flashes. The ISI plays a large role in the phi phenomenon (Wertheimer) since the illusion of motion is directly due to the length of the interval between stimuli. When the ISI is shorter, for example between two flashing lines alternating back and forth, we perceive the change in stimuli to be movement. [1] Wertheimer discovered that the space between the two lines is filled in by our brains and that the faster the lines alternate, the more likely we are to perceive it as one line moving back and forth. [1] When the stimuli move fast enough, this creates the illusion of a moving picture like a movie or cartoon. Phi phenomenon is very similar to beta movement. [1]

As it applies to classical conditioning, the term interstimulus interval is used to represent the gap of time between the start of the neutral or conditioned stimulus and the start of the unconditioned stimulus. [2] An example would be the case of Pavlov's dog, where the time between the unconditioned stimulus, the food, and the conditioned stimulus, the bell, is considered the ISI. More particularly, ISI is often used in eyeblink conditioning (a widely studied type of classical conditioning involving puffs of air blown into the subject's eyes) where the ISI can affect learning based on the size of the time gap. [2] What is of interest in this particular type of classical conditioning is that when the subject is conditioned to blink after the conditioned stimulus (tone), the blink will take place within the time period between the tone and the air puff, making the subject's eyes close before the puff can reach the eyes, protecting them from the air. [2]

The timing between the conditioned and unconditioned stimulus is important. There are two types of approaches for eye blink conditioning when it comes to timing between the stimuli. The first is called delay conditioning, which is when the conditioned stimulus (tone) starts, then continues until the unconditioned stimulus (air puff) is released after a delay, then they both suspend at the same time. [2] The other is called trace conditioning, where the conditioned stimulus (tone) is shorter and stops before the unconditioned stimulus (air puff) begins, leaving a gap between the two stimuli. [2] This type of conditioning forces the subject, in this particular example, a bunny, to remember to link the conditioned stimulus with the unconditioned stimulus. [2]

The distinction between the two types of conditioning is of importance because the difference in the interstimulus interval (ISI) can have major effects on learning. [2] For example, it has been shown that the length of the ISI, as well as the variability, changes habituation in subjects. [3] When ISI is short and constant, habituation will happen more rapidly. [3] The changes in the gap of time can be minuscule, from tens of milliseconds to several seconds long, and the effects it will have will still be important. [4] Sensory and motor tasks are among the elements that can be enhanced or hindered based on timing, like speech processing, which can be influenced by "the ability to discriminate the interval and duration of sounds." [4]

Related Research Articles

Classical conditioning is a behavioral procedure in which a biologically potent physiological stimulus is paired with a neutral stimulus. The term classical conditioning refers to the process of an automatic, conditioned response that is paired with a specific stimulus.

<span class="mw-page-title-main">Phi phenomenon</span> Optical illusion of apparent motion

The term phi phenomenon is used in a narrow sense for an apparent motion that is observed if two nearby optical stimuli are presented in alternation with a relatively high frequency. In contrast to beta movement, seen at lower frequencies, the stimuli themselves do not appear to move. Instead, a diffuse, amorphous shadowlike something seems to jump in front of the stimuli and occlude them temporarily. This shadow seems to have nearly the color of the background. Max Wertheimer first described this form of apparent movement in his habilitation thesis, published 1912, marking the birth of Gestalt psychology.

<span class="mw-page-title-main">Absolute threshold of hearing</span> Minimum sound level that an average human can hear

The absolute threshold of hearing (ATH) is the minimum sound level of a pure tone that an average human ear with normal hearing can hear with no other sound present. The absolute threshold relates to the sound that can just be heard by the organism. The absolute threshold is not a discrete point and is therefore classed as the point at which a sound elicits a response a specified percentage of the time. This is also known as the auditory threshold.

Eyeblink conditioning (EBC) is a form of classical conditioning that has been used extensively to study neural structures and mechanisms that underlie learning and memory. The procedure is relatively simple and usually consists of pairing an auditory or visual stimulus with an eyeblink-eliciting unconditioned stimulus (US). Naïve organisms initially produce a reflexive, unconditioned response (UR) that follows US onset. After many CS-US pairings, an association is formed such that a learned blink, or conditioned response (CR), occurs and precedes US onset. The magnitude of learning is generally gauged by the percentage of all paired CS-US trials that result in a CR. Under optimal conditions, well-trained animals produce a high percentage of CRs. The conditions necessary for, and the physiological mechanisms that govern, eyeblink CR learning have been studied across many mammalian species, including mice, rats, guinea pigs, rabbits, ferrets, cats, and humans. Historically, rabbits have been the most popular research subjects.

Habituation is a form of non-associative learning in which an innate (non-reinforced) response to a stimulus decreases after repeated or prolonged presentations of that stimulus. Responses that habituate include those that involve the intact organism or those that involve only components of the organism. The broad ubiquity of habituation across all biologic phyla has resulted in it being called "the simplest, most universal form of learning...as fundamental a characteristic of life as DNA." Functionally-speaking, by diminishing the response to an inconsequential stimulus, habituation is thought to free-up cognitive resources to other stimuli that are associated with biologically important events. For example, organisms may habituate to repeated sudden loud noises when they learn these have no consequences. A progressive decline of a behavior in a habituation procedure may also reflect nonspecific effects such as fatigue, which must be ruled out when the interest is in habituation. Habituation is clinically relevant, as a number of neuropsychiatric conditions, including autism, schizophrenia, migraine, and Tourette's, show reductions in habituation to a variety of stimulus-types both simple (tone) and complex (faces).

<span class="mw-page-title-main">Beta movement</span>

The term Beta movement is used for the optical illusion of apparent motion in which the very short projection of one figure and a subsequent very short projection of a more or less similar figure in a different location are experienced as one figure moving.

The Rescorla–Wagner model ("R-W") is a model of classical conditioning, in which learning is conceptualized in terms of associations between conditioned (CS) and unconditioned (US) stimuli. A strong CS-US association means that the CS signals predict the US. One might say that before conditioning, the subject is surprised by the US, but after conditioning, the subject is no longer surprised, because the CS predicts the coming of the US. The model casts the conditioning processes into discrete trials, during which stimuli may be either present or absent. The strength of prediction of the US on a trial can be represented as the summed associative strengths of all CSs present during the trial. This feature of the model represented a major advance over previous models, and it allowed a straightforward explanation of important experimental phenomena, most notably the blocking effect. Failures of the model have led to modifications, alternative models, and many additional findings. The model has had some impact on neural science in recent years, as studies have suggested that the phasic activity of dopamine neurons in mesostriatal DA projections in the midbrain encodes for the type of prediction error detailed in the model.

Conditioned taste aversion occurs when an animal acquires an aversion to the taste of a food that was paired with aversive stimuli. The Garcia effect explains that the aversion develops more strongly for stimuli that cause nausea than other stimuli. This is considered an adaptive trait or survival mechanism that enables the organism to avoid poisonous substances before they cause harm. The aversion reduces consuming the same substance in the future, thus avoiding poisoning.

<span class="mw-page-title-main">Shaping (psychology)</span> Psychological paradigm for behavior analysis

Shaping is a conditioning paradigm used primarily in the experimental analysis of behavior. The method used is differential reinforcement of successive approximations. It was introduced by B. F. Skinner with pigeons and extended to dogs, dolphins, humans and other species. In shaping, the form of an existing response is gradually changed across successive trials towards a desired target behavior by reinforcing exact segments of behavior. Skinner's explanation of shaping was this:

We first give the bird food when it turns slightly in the direction of the spot from any part of the cage. This increases the frequency of such behavior. We then withhold reinforcement until a slight movement is made toward the spot. This again alters the general distribution of behavior without producing a new unit. We continue by reinforcing positions successively closer to the spot, then by reinforcing only when the head is moved slightly forward, and finally only when the beak actually makes contact with the spot. ... The original probability of the response in its final form is very low; in some cases it may even be zero. In this way we can build complicated operants which would never appear in the repertoire of the organism otherwise. By reinforcing a series of successive approximations, we bring a rare response to a very high probability in a short time. ... The total act of turning toward the spot from any point in the box, walking toward it, raising the head, and striking the spot may seem to be a functionally coherent unit of behavior; but it is constructed by a continual process of differential reinforcement from undifferentiated behavior, just as the sculptor shapes his figure from a lump of clay.

Extinction is a behavioral phenomenon observed in both operantly conditioned and classically conditioned behavior, which manifests itself by fading of non-reinforced conditioned response over time. When operant behavior that has been previously reinforced no longer produces reinforcing consequences the behavior gradually stops occurring. In classical conditioning, when a conditioned stimulus is presented alone, so that it no longer predicts the coming of the unconditioned stimulus, conditioned responding gradually stops. For example, after Pavlov's dog was conditioned to salivate at the sound of a metronome, it eventually stopped salivating to the metronome after the metronome had been sounded repeatedly but no food came. Many anxiety disorders such as post traumatic stress disorder are believed to reflect, at least in part, a failure to extinguish conditioned fear.

An avoidance response is a natural adaptive behavior performed in response to danger. Excessive avoidance has been suggested to contribute to anxiety disorders, leading psychologists and neuroscientists to study how avoidance behaviors are learned using rat or mouse models. Avoidance learning is a type of operant conditioning.

The study of time perception or chronoception is a field within psychology, cognitive linguistics and neuroscience that refers to the subjective experience, or sense, of time, which is measured by someone's own perception of the duration of the indefinite and unfolding of events. The perceived time interval between two successive events is referred to as perceived duration. Though directly experiencing or understanding another person's perception of time is not possible, perception can be objectively studied and inferred through a number of scientific experiments. Some temporal illusions help to expose the underlying neural mechanisms of time perception.

Echoic memory is the sensory memory that registers specific to auditory information (sounds). Once an auditory stimulus is heard, it is stored in memory so that it can be processed and understood. Unlike most visual memory, where a person can choose how long to view the stimulus and can reassess it repeatedly, auditory stimuli are usually transient and cannot be reassessed. Since echoic memories are heard once, they are stored for slightly longer periods of time than iconic memories. Auditory stimuli are received by the ear one at a time before they can be processed and understood.

<span class="mw-page-title-main">Blocking effect</span> Elaboration on classical conditioning in psychology

In Kamin's blocking effect the conditioning of an association between two stimuli, a conditioned stimulus (CS) and an unconditioned stimulus (US) is impaired if, during the conditioning process, the CS is presented together with a second CS that has already been associated with the unconditioned stimulus.

The contingent negative variation (CNV) is a negative slow surface potential, as measured by electroencephalography (EEG), that occurs during the period between a warning stimulus or signal and an imperative ("go") stimulus. The CNV was one of the first event-related potential (ERP) components to be described. The CNV component was first described by W. Grey Walter and colleagues in an article published in Nature in 1964. The importance of this finding was that it was one of the first studies which showed that consistent patterns of the amplitude of electric responses could be obtained from the large background noise which occurs in EEG recordings and that this activity could be related to a cognitive process such as expectancy.

<span class="mw-page-title-main">Conditioned place preference</span> Pavlovian conditioning

Conditioned place preference (CPP) is a form of Pavlovian conditioning used to measure the motivational effects of objects or experiences. This motivation comes from the pleasurable aspect of the experience, so that the brain can be reminded of the context that surrounded the "encounter". By measuring the amount of time an animal spends in an area that has been associated with a stimulus, researchers can infer the animal's liking for the stimulus. This paradigm can also be used to measure conditioned place aversion with an identical procedure involving aversive stimuli instead. Both procedures usually involve mice or rats as subjects. This procedure can be used to measure extinction and reinstatement of the conditioned stimulus. Certain drugs are used in this paradigm to measure their reinforcing properties. Two different methods are used to choose the compartments to be conditioned, and these are biased vs. unbiased. The biased method allows the animal to explore the apparatus, and the compartment they least prefer is the one that the drug is administered in and the one they most prefer is the one where the vehicle is injected. This method allows the animal to choose the compartment they get the drug and vehicle in. In comparison, the unbiased method does not allow the animal to choose what compartment they get the drug and vehicle in and instead the researcher chooses the compartments.

The P3a, or novelty P3, is a component of time-locked (EEG) signals known as event-related potentials (ERP). The P3a is a positive-going scalp-recorded brain potential that has a maximum amplitude over frontal/central electrode sites with a peak latency falling in the range of 250–280 ms. The P3a has been associated with brain activity related to the engagement of attention and the processing of novelty.

The term conditioned emotional response (CER) can refer to a specific learned behavior or a procedure commonly used in classical or Pavlovian conditioning research. It may also be called "conditioned suppression" or "conditioned fear response (CFR)." It is an "emotional response" that results from classical conditioning, usually from the association of a relatively neutral stimulus with a painful or fear-inducing unconditional stimulus. As a result, the formerly neutral stimulus elicits fear. For example, if seeing a dog is paired with the pain of being bitten by the dog, seeing a dog may become a conditioned stimulus that elicits fear.

External inhibition is the observed decrease of the response of a conditioned reaction when an external (distracting) stimulus that was not part of the original conditioned response set is introduced. This effect was first observed in Ivan Pavlov's classical conditioning studies where the dogs would salivate less when presented with the sound of the tuning fork in the distracting context of a passing truck. External inhibition is important for its main principle in classical conditioning where a conditioned response may decrease in magnitude after the external stimulus is introduced. This is especially advantageous for when trying to disassociate conditioned stimulus and responses. A practical example is where students who become anxious upon standing in front of the class to give a presentation may feel less anxiety if their friends were sitting in front of the student presenting. The positive association of speaking to friends may distract the student from associating speaking to the entire class with anxiety.

The Perruchet effect is a psychological phenomenon in which a dissociation is shown between conscious expectation of an event and the strength or speed of a response to the event. This can be demonstrated by sequential analyses of consecutive trials such as eye blinking conditioning, electrodermal shocks and cued go/no-go task. The dissociation design differentiates the automatic associative strength and propositional expectation's effects on associative learning and conditioning, i.e., the cognitive learning process with relationship between events.

References

  1. 1 2 3 Cummins, E. (n.d.). The Phi Phenomenon: Definition & Example. Retrieved May 03, 2016, from http://study.com/academy/lesson/the-phi-phenomenon-definition-lesson.html
  2. 1 2 3 4 5 6 7 Gluck, Mark A.; Mercado, Eduardo; Myers, Catherine E. (January 7, 2013). Learning and Memory: From Brain to Behavior. New York, NY: Worth Publishers. pp. 124–146. ISBN   978-1429240147.
  3. 1 2 Davis, M. (1970). Effects of interstimulus interval length and variability on startle-response habituation in the rat. Journal of Comparative and Physiological Psychology, 72(2), 177-192. doi : 10.1037/h0029472
  4. 1 2 Buonomano, D. V., Bramen, J., & Khodadadifar, M. (2009). Influence of the interstimulus interval on temporal processing and learning: Testing the state-dependent network model. Philosophical Transactions of the Royal Society B: Biological Sciences,364(1525), 1865-1873. doi : 10.1098/rstb.2009.0019