SJSU PSYC 158 Exam 1 Questions + Answers Graded A+

The JND is a constant fraction of the stimulus. - ️️•JND / I = K I= intensity of the standard K = a constant that is characteristic of the task ("Weber fraction") conditions: - ️️-cataract - an opaque (or less transparent) area in the lens•some caused by UV in sunlight; common in aged•cured by removing lens, use glasses instead (but...) perception - ️️conscious experience of objects and their relationships (resulting from psychological processes in which meaning, relationships, context, judgment, past experience, and memory may play a role) -e.g., your awareness of seeing a cat Psychophysics - ️️the study of the quantitative relationship between physical properties of the world and our psychological perception of these properties Gustav Fechner absolute threshold - ️️the smallest amount of stimulus energy necessary to detect a stimulus•e.g., What is the dimmest light that you can detect? psychometric function - ️️curve of percentage detection versus intensity I. Method of Limits - ️️begin with undetectable stimulus; gradually increase intensity until subject detects it (and vice versa)• subject responds yes or no below threshold, you would never detect above threshold, you would always detect absolute threshold is the intensity that is detected 50% of the time II. Method of Adjustment - ️️•a variant of Method of Limits •start with undetectable stimulus •subject presses button to make stimulus stronger•stop when they detect the stimulus •(and vice versa - start with detectable and adjust until undetectable) III. Method of Constant Stimuli - ️️•similar to Method of Limits, except stimuli are not presented in order of strength (rather, random order) •subject does not know what change to expect sensation - ️️initial processes of detecting and encoding environmental energy Difference Threshold - ️️•a.k.a. just noticeable difference (JND) •smallest difference between two stimuli that a person can detect •as the magnitude of the stimulus increases, the difference threshold increases physiological - ️️-invasive •lesion •ablation - creating lesions •single cell recordings non-invasive - ️️•EEG - electrical fields •fMRI, PET, CAT - brain imaging •TMS - magnetic shock temporarily disrupts region psychological - ️️-detection-discrimination - telling the difference between 2 stimuli-matching - pick the one that matches the model-scaling - ordering-identification photons - ️️- tiny particles of light; the smallest units of light waves - ️️- tiny oscillations of molecules wavelength - ️️- how far the wave travels between oscillationsthe visible spectrum is just a part of the possible electromagnetic radiation - ️️400- 700 nm lateral - ️️-wide range of vision -prey frontal - ️️-overlap helps for 3D vision -predators cornea - ️️- transparent protective coating over front of eye pupil - ️️- small opening in center of eye, through which light enters eye -expands and contracts to let more or less light in -also opens when autonomic nervous system is aroused (excitement, fear, sexual arousal) iris - ️️- colored part of eye surrounding pupil lens - ️️- transparent part of eye inside pupil that focuses light onto retina -brunescence - gradual yellowing of lens with age due to UV-sclerosis - hardening of the lens with age retina - ️️- inner surface of back of eye; receives image and sends it to brain Light in the Eye - ️️•image on retina is upside-down and right-left reversed refraction - ️️- incoming light rays are bent -rays focus on the retina accommodation - ️️- making the lens thicker (or thinner) to focus objects that are closer (or farther) emmetropia (i.e., good vision) - ️️-eye can focus an object exactly on retina -due to the power of the eye's optics matching the length of the eyeballmyopia (near-sightedness) - ️️-image of a distant target is focused in front of the retina -eyeball too long; or lens too strong -see near objects clearly, but far objects blurred