MCAT Psychological Social Foundations Flashcards: 6a Sensation Thresholds Psychophysics

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This deck focuses on 6a Sensation Thresholds Psychophysics, giving you a quick way to review the definitions, rules, and examples that matter most for MCAT Psychological Social Foundations.

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Flashcard 1: What is perceptual set?

Answer: Top-down predisposition to perceive stimuli in a particular way. Expectations shape how we interpret stimuli.

Flashcard 2: Using Weber's law, what is $\Delta I$ if $I=100$ and $k=0.05$?

Answer: $\Delta I=5$. Apply Weber's law: $\Delta I = k \times I = 0.05 \times 100$.

Flashcard 3: What is the decision criterion in signal detection theory?

Answer: Response bias threshold for saying "signal present". Reflects observer's willingness to report detecting a signal.

Flashcard 4: What is the difference threshold (just noticeable difference, JND)?

Answer: Smallest detectable difference between two stimuli. Minimum change needed to perceive a difference.

Flashcard 5: Using Weber's law, find $\Delta I$ if $I=100$ and $k=0.05$.

Answer: $\Delta I=5$. $\Delta I = kI = 0.05 \times 100 = 5$

Flashcard 6: What is a hit in signal detection theory?

Answer: Reporting a signal when the signal is present. Correct positive response in detection task.

Flashcard 7: In signal detection theory, what is a miss?

Answer: Signal present but the observer reports "signal absent". Failure to detect when signal is actually present.

Flashcard 8: What does the exponent $a$ indicate in Stevens' power law $P=kI^a$?

Answer: Modality-specific scaling; $a>1$ expands, $a<1$ compresses. Exponent varies by sensory modality (e.g., brightness vs. loudness).

Flashcard 9: What is the absolute threshold in psychophysics?

Answer: Minimum intensity detected $50\%$ of the time. The absolute threshold represents the point at which a stimulus becomes detectable half the time, marking the lower limit of sensory sensitivity.

Flashcard 10: If the decision criterion becomes more liberal, how do false alarms change?

Answer: False alarms increase. Liberal criterion means saying "yes" more often.

Flashcard 11: State Stevens' power law relating perceived magnitude $S$ to intensity $I$.

Answer: $S=kI^a$. Power function; exponent $a$ varies by sensory modality.

Flashcard 12: What is Stevens' power law relating perceived magnitude to intensity?

Answer: $P=kI^n$. Stevens' power law describes how perceived sensation magnitude scales with physical intensity through a power function, varying by sensory modality.

Flashcard 13: State Weber's law for the relationship between JND and stimulus intensity.

Answer: $\frac{\Delta I}{I}=k$ (constant proportion for a given sense). The ratio of change to original intensity stays constant.

Flashcard 14: In Stevens' power law, which condition holds when $0<n<1$: compression or expansion?

Answer: Compression (perceived intensity grows slower than stimulus). Exponent $<1$ means sensation increases slower than stimulus.

Flashcard 15: Identify the outcome: signal absent and participant says "no."

Answer: Correct rejection. Correctly identifying absence of signal.

Flashcard 16: Which term describes decreased sensitivity due to constant, unchanging stimulation?

Answer: Sensory adaptation. Receptors become less responsive to unchanging stimuli.

Flashcard 17: What is the absolute threshold?

Answer: Minimum stimulus intensity detected $50\%$ of the time. Statistical threshold for reliable detection.

Flashcard 18: Under Fechner's law, if $I$ increases by a factor of $10$, how does $S$ change?

Answer: It increases by an additive constant of $k$. Log of 10-fold increase adds $k\log(10)$ to sensation.

Flashcard 19: State Weber's law for the JND.

Answer: $\frac{\Delta I}{I}=k$ (constant proportion for a given modality). JND is a constant fraction of stimulus intensity.

Flashcard 20: If $\Delta I=4$ at $I=80$, what is the Weber fraction $k$?

Answer: $k=0.05$. Rearrange Weber's law: $k = \frac{\Delta I}{I} = \frac{4}{80}$.

Flashcard 21: Using Weber's law, what is the new intensity at JND if $I=80$ and $k=0.25$?

Answer: $I+\Delta I=80+(0.25\times 80)=100$. Add JND to baseline: $80 + (0.25 \times 80) = 80 + 20$.

Flashcard 22: In signal detection theory, what is a hit?

Answer: Signal present and the observer reports "signal present". Correct detection when signal is actually present.

Flashcard 23: Using Weber's law, if $k=0.10$ and $I=50$, what is $\Delta I$?

Answer: $\Delta I=5$. Apply Weber's law: $\Delta I = k \times I = 0.10 \times 50$.

Flashcard 24: What is the difference threshold (just noticeable difference, JND)?

Answer: Smallest detectable difference between two stimuli. Also called JND; follows Weber's law.

Flashcard 25: State Weber's law using a formula for the JND.

Answer: $\frac{\Delta I}{I}=k$. JND is proportional to stimulus intensity; $k$ is Weber's constant.

Flashcard 26: What is the psychophysical relationship described by Stevens' power law?

Answer: Perceived intensity $P=kS^n$ relates nonlinearly to stimulus $S$. Sensation grows as a power function of stimulus strength.

Flashcard 27: If $n=1$ in Stevens' power law, what is the relationship between $P$ and $I$?

Answer: Linear: $P\propto I$. An exponent of 1 results in a direct proportional relationship, meaning perceived magnitude matches stimulus intensity linearly.

Flashcard 28: What is signal detection theory primarily used to model in perception?

Answer: Detection of weak signals under uncertainty and decision bias effects. Accounts for both sensory ability and decision-making factors in detection.

Flashcard 29: Identify the absolute threshold rule: at threshold, a stimulus is detected what percent of trials?

Answer: $50\%$. Definition of absolute threshold requires 50% detection rate.

Flashcard 30: Using Weber's law, if $\Delta I=2$ and $I=40$, what is $k$?

Answer: $k=0.05$. Rearrange Weber's law: $k = \frac{\Delta I}{I} = \frac{2}{40}$.

Flashcard 31: Which response occurs when you report a signal is present when it is absent?

Answer: False alarm. Type I error: saying "yes" when the answer is "no".

Flashcard 32: What is the absolute threshold in psychophysics?

Answer: Minimum stimulus intensity detected $50\%$ of the time. Below this intensity, stimuli cannot be reliably detected.

Flashcard 33: What is a psychophysical method of limits used to measure?

Answer: Thresholds via ascending/descending stimulus series. The method of limits determines perceptual thresholds by systematically varying stimulus intensity in series to find detection boundaries.

Flashcard 34: Identify $\Delta I$ in Weber's law $\frac{\Delta I}{I}=k$.

Answer: $\Delta I$ is the JND: smallest detectable change in intensity. The numerator represents the minimum detectable change.

Flashcard 35: Which response occurs when you fail to report a signal that is present?

Answer: Miss (false negative). Type II error: failing to detect an actual signal.

Flashcard 36: What is the distinction between sensation and perception?

Answer: Sensation detects stimuli; perception organizes and interprets them. Sensation is raw input; perception is meaningful interpretation.

Flashcard 37: What is sensory adaptation?

Answer: Reduced sensitivity after prolonged exposure to an unchanging stimulus. Receptors decrease firing rate to constant stimuli over time.

Flashcard 38: What does a smaller Weber fraction $k$ imply about sensory sensitivity?

Answer: Greater sensitivity (smaller proportional change needed to detect a difference). Lower $k$ means smaller changes are detectable, indicating better sensitivity.

Flashcard 39: What is sensation in the context of perception?

Answer: Detection and transduction of physical energy into neural signals. Raw sensory input before brain processing creates meaning.

Flashcard 40: What is perception in relation to sensory input?

Answer: Interpretation and organization of sensory information into meaning. The brain processes sensory signals to create meaningful experiences.

Flashcard 41: In signal detection theory, what is a miss?

Answer: Signal present but the observer reports "no". Failing to detect a signal that is actually present.

Flashcard 42: In Stevens' power law, what does $a>1$ indicate about perceived growth?

Answer: Perception grows faster than intensity (expansive function). Perceived intensity increases faster than actual intensity.

Flashcard 43: Which option best defines signal detection theory (SDT)?

Answer: Detection depends on signal strength and observer criteria (bias). Accounts for both sensory ability and decision-making.

Flashcard 44: What is signal detection theory primarily used to explain about thresholds?

Answer: Detection depends on sensitivity and decision criterion. Signal detection theory accounts for both the observer's perceptual sensitivity and their response bias in determining whether a stimulus is detected.

Flashcard 45: Which psychophysical method presents many fixed intensities in random order to estimate a threshold?

Answer: Method of constant stimuli. Statistical approach using multiple trials at each intensity.

Flashcard 46: What is the formula for false alarm rate in a yes/no signal detection task?

Answer: $\text{FA rate}=\frac{\text{false alarms}}{\text{false alarms}+\text{correct rejections}}$. Proportion of noise trials incorrectly called signals.

Flashcard 47: Which outcome is a "hit" in signal detection theory?

Answer: Signal present and the observer responds "yes". Correctly detecting a signal when it's actually present.

Flashcard 48: What is sensation in the context of sensory processing?

Answer: Detection and transduction of physical stimuli into neural signals. Sensation occurs before perception in the processing chain.

Flashcard 49: Which option best defines psychophysics?

Answer: Study of relationships between physical stimuli and perceived sensations. Quantifies how physical stimuli become psychological experiences.

Flashcard 50: What is the key difference between sensory adaptation and habituation?

Answer: Adaptation is receptor-level; habituation is CNS-level learning. Adaptation is peripheral; habituation involves higher processing.

Flashcard 51: State Fechner's law relating perceived sensation to stimulus intensity.

Answer: $S=k\log(I)$. Logarithmic relationship between stimulus and sensation.

Flashcard 52: What is transduction in the context of sensation?

Answer: Conversion of physical stimulus energy into neural signals. Sensory receptors convert stimuli to action potentials.

Flashcard 53: Which change in criterion increases hits but also increases false alarms?

Answer: A more liberal (lower) decision criterion. Lowering the decision criterion makes observers more likely to report signals, boosting true detections but also erroneous positives.

Flashcard 54: State Stevens' power law for perceived intensity as a function of intensity.

Answer: Perception follows a power function: $S=kI^a$. More accurate than Fechner's log law for most senses.

Flashcard 55: State Stevens' power law relating perceived magnitude to stimulus intensity.

Answer: $S=kI^a$. Power function better fits data than Fechner's log law.

Flashcard 56: In signal detection theory, what is a "correct rejection"?

Answer: No signal present and the observer reports "no signal". A correct rejection is accurately determining no signal is present, demonstrating effective discrimination in signal detection scenarios.

Flashcard 57: Identify the concept: detection depends on stimulus strength and psychological factors like fatigue and expectations.

Answer: Signal detection theory. This theory explains how detection involves both sensory and decision factors.

Flashcard 58: What is a correct rejection in signal detection theory?

Answer: Reporting no signal when no signal is present. Correct negative response in detection task.

Flashcard 59: What is signal detection theory primarily used to explain in threshold tasks?

Answer: Detecting signals amid noise using sensitivity and decision criteria. Separates sensory ability from response bias in detection tasks.

Flashcard 60: What is the difference threshold (just-noticeable difference, JND)?

Answer: Smallest detectable difference between two stimuli $50\%$ of the time. Statistical threshold for discriminating between similar stimuli.

Flashcard 61: What is the formula for hit rate in a yes/no signal detection task?

Answer: $\text{Hit rate}=\frac{\text{hits}}{\text{hits}+\text{misses}}$. Proportion of signals correctly identified as present.

Flashcard 62: State Weber's law for difference thresholds.

Answer: $\frac{\Delta I}{I}=k$. Weber's law states that the just noticeable difference is a constant proportion of the original stimulus intensity, explaining relative perceptual changes.

Flashcard 63: In SDT, what is a false alarm?

Answer: Signal absent but the observer reports detecting it. Incorrectly reporting a signal when none exists.

Flashcard 64: In signal detection theory, what does a more conservative response criterion produce?

Answer: Fewer false alarms and more misses. Higher threshold reduces false positives but increases misses.

Flashcard 65: Which principle states that perceived change depends on proportional, not absolute, change?

Answer: Weber's law. Describes how JND scales with stimulus intensity.

Flashcard 66: Which outcome is a "correct rejection" in signal detection theory?

Answer: No signal present and the observer responds "no". Correctly reporting no signal when only noise is present.

Flashcard 67: Identify the meaning of $k$ in Weber's law $\frac{\Delta I}{I}=k$.

Answer: Weber fraction; modality-specific constant of proportional sensitivity. Ratio remains constant within each sensory modality.

Flashcard 68: In signal detection theory, what is sensitivity ($d'$)?

Answer: Ability to distinguish signal from noise; higher $d'$ means better detection. Measures true detection ability independent of response bias.

Flashcard 69: Using Weber's law, what is $\Delta I$ if $I=40$ and $k=0.10$?

Answer: $\Delta I=4$. Weber's law calculates the just noticeable difference as a fixed ratio of the baseline intensity, yielding $\Delta I = k \times I$.

Flashcard 70: Which option describes a liberal criterion in signal detection theory?

Answer: More hits and more false alarms (lower threshold to say "yes"). Lenient responder catches more signals but makes more errors.

Flashcard 71: What is a false alarm in signal detection theory?

Answer: Reporting a signal when no signal is present. Type I error in signal detection.

Flashcard 72: Identify the outcome: signal present and participant says "yes."

Answer: Hit. Correctly detecting a present signal.

Flashcard 73: In signal detection theory, what is sensitivity ($d'$)?

Answer: Ability to discriminate signal from noise (higher $d'$ = better). Measures pure detection ability independent of bias.

Flashcard 74: Using Weber's law, what is $k$ if $I=200$ and $\Delta I=10$?

Answer: $k=0.05$. Rearrange Weber's law: $k = \frac{\Delta I}{I} = \frac{10}{200}$.

Flashcard 75: What is sensation in the context of perception and psychophysics?

Answer: Detection of physical stimuli by sensory receptors. Sensation involves the initial process where sensory receptors respond to environmental stimuli, converting them into neural impulses for further processing.

Flashcard 76: What is the absolute threshold in psychophysics?

Answer: Minimum stimulus intensity detected $50\%$ of the time. Below this intensity, stimuli go undetected.

Flashcard 77: In Stevens' power law, what does $0<a<1$ indicate about perceived growth?

Answer: Perception grows slower than intensity (compressive function). Perceived intensity increases slower than actual intensity.

Flashcard 78: In signal detection theory, what is a "false alarm"?

Answer: No signal present but the observer reports "signal". A false alarm results from reporting a signal when none exists, typically influenced by a liberal response bias in signal detection theory.

Flashcard 79: Using Weber's law, what is $\Delta I$ if $I=50$ and $k=0.10$?

Answer: $\Delta I=kI=5$. Apply Weber's law: $\Delta I = k \times I = 0.10 \times 50$.

Flashcard 80: What is the general idea of Stevens' power law relating perceived magnitude to intensity?

Answer: $P=kI^a$ (perceived magnitude is a power function of intensity). Replaces Weber's linear ratio with exponential relationship.

Flashcard 81: What is sensation in psychology?

Answer: Detection and transduction of physical stimuli into neural signals. Raw sensory input before brain processing.

Flashcard 82: In signal detection theory, what is a hit?

Answer: Signal present and the observer reports "yes". Correctly detecting a signal that is actually present.

Flashcard 83: What is the psychophysical method of adjustment used to estimate?

Answer: Thresholds by having the participant adjust intensity to detectability. Participant controls stimulus to find their own threshold.

Flashcard 84: State Weber's law using stimulus intensity $I$ and JND $\Delta I$.

Answer: $\frac{\Delta I}{I}=k$ (constant Weber fraction). JND is proportional to stimulus intensity; ratio stays constant.

Flashcard 85: In SDT, what is a hit?

Answer: Signal present and the observer reports detecting it. Correctly identifying a present signal.

Flashcard 86: In signal detection theory, what is a correct rejection?

Answer: Signal absent and the observer reports "signal absent". Correctly identifying absence of signal.

Flashcard 87: What is transduction in the context of sensation?

Answer: Conversion of physical stimulus energy into neural signals. Receptors convert light, sound, etc. to action potentials.

Flashcard 88: State Fechner's law relating perceived intensity to stimulus intensity.

Answer: $S=k\log\left(\frac{I}{I_0}\right)$. Logarithmic relationship means equal ratios feel like equal differences.

Flashcard 89: Identify the term for the relationship between actual stimulus intensity and perceived intensity.

Answer: Psychophysical scaling. Maps physical intensity to subjective experience.

Flashcard 90: State Weber's law for the JND as a formula.

Answer: $\frac{\Delta I}{I}=k$. JND is proportional to stimulus intensity.

Flashcard 91: What is the absolute threshold in sensation and perception?

Answer: Minimum stimulus intensity detected $50\%$ of the time. The point where detection probability equals chance.

Flashcard 92: In SDT, what is a correct rejection?

Answer: Signal absent and the observer reports not detecting it. Correctly identifying no signal is present.

Flashcard 93: What is the absolute threshold in sensation and perception?

Answer: Minimum stimulus intensity detected $50\%$ of the time. The threshold where detection probability equals chance.

Flashcard 94: What is signal detection theory primarily used to explain?

Answer: Detecting weak signals amid noise using decision criteria. Separates sensory ability from response bias.

Flashcard 95: What is signal detection theory primarily used to explain in threshold tasks?

Answer: Detection depends on sensitivity and decision criterion under uncertainty. Separates sensory sensitivity from response bias.

Flashcard 96: If the response criterion becomes more conservative, what happens to hits and false alarms?

Answer: Hits decrease and false alarms decrease. Conservative criterion means saying "yes" less often, reducing both outcomes.

Flashcard 97: In signal detection theory, what does response criterion ($\beta$) represent?

Answer: Decision threshold for saying "signal present". Influenced by expectations and consequences of errors.

Flashcard 98: Which option best defines response bias in signal detection theory?

Answer: Tendency to favor one response (yes/no) independent of sensitivity. Reflects decision criterion, not actual sensitivity.

Flashcard 99: What is the psychophysical method of limits?

Answer: Ascending/descending trials to estimate sensory thresholds. Systematically varies intensity to find threshold.

Flashcard 100: Identify the four outcomes in signal detection theory for a yes/no task.

Answer: Hit, miss, false alarm, correct rejection. 2×2 matrix: signal present/absent × response yes/no.