Cognitive Neuroscience (Top-Down / Bottom-up) Flashcards
What is Cognitive Neuroscience?
Cognitive neuroscience is concerned with the biological processes that underlie cognition, with a specific focus on the neural connections in the brain which are involved in mental processes.
How does the Cognitive neuroscience approach usually study Language processing?
by using dichotic listening studies and brain imaging.
what is REA?
REA is a neurocognitive measure of speech perception asymmetry.
Subjects with left-hemispheric language lateralization, which possibly constitute more than 95 percent of the population are more accurate in reporting signals arriving at the right ear than signals arriving at the left ear when the input is verbal.
What is the experimental procedure of dichotic listening?
The participant is presented with two different auditory stimuli simultaneously. The different stimuli are directed into different ears over headphones.
Do the Trace Model (McClelland and Elman 1986) and the Auditory sentence processing model (Friederici 2002) believe that Top down processing or Bottom up processing occurs in Language comprehension?
Which happen first?
Claim that both types of processing are necessary.
Following these models it is generally accepted that bottom-up processing (acoustic processing of incoming signals) happens first wheras top-down processes i.e the recognition based on knowledge of phonemes , semantics or syntax takes effect at a later stage of perception.
Which dichotic listening studies support bottom-up?
Schwartz and tallal (1980)
Rimol (2006)
What dichotic listening stidies suppot top-down?
Cowell and hugdahl (2000)
What was Schwartz and Tallal’s (1980) method?
Conducted a Dichotic listening study with 15 participants using the acoustic stimuli (/pa/ta/ka/ba/da/ga/).
First set :
CV syllables with a formant transition of 40 msecs were presented dichotically
Second Set:
CV syllables with formant transition of 80msec (/pa/ta/ka vs /ba/da/ga).
What did Schwartz and Tallal (1980) find?
REA observed for 40msec but not 80msec formant transitions
What did Schwartz and Tallals finding’s show regarding bottom up / top down processing?
Because the sets of stimuli were similar along phonetic verbal dimensions (top down) but differed along auditory temporal dimensions (bottom up), by altering the temporal component of acoustic spectra within speech sounds changes the magnitude of REA - therefore bottom up processing exists.
What did Rimol (2006) investigate?
Investigated the effect of voice-onset-time (VOT) in dichotic listening with consonant–vowel (CV) syllables.
What was Rimol’s (2006) Method?
Eighty-nine subjects with (REA) were tested with DL test.
Used three CV syllables with short VOT /ba, da, ga/ and three syllables with long VOT /pa, ta, ka/.
Four possible combinations when CV syllables presented dichotically : short–long (SL), (i.e. syllable-pairs with a short VOT in the left ear and a syllable with a long VOT in the right ear) ; and similarly long–short (LS), short–short (SS), and long–long (LL).
What did Rimol (2006) find?
Syllable pairs with long VOT presented in the right ear and short VOT in the left ear, produced the largest REA. This was followed by the LL and SS conditions.
The LS condition produced a significant left-ear-advantage (LEA).
These results demonstrate that VOT significantly affects ear-advantage as observed in the DL test and suggest that VOT may be a more powerful determinant of DL performance than the classic REA effect.
What are the implications of both Rimol’s (2006) and Schwartz and Tallal’s (1980) studies?
Studies shows that there are two bottom up factors which play an important role in determining ear advantage in the DL test:
- Type of stimuli - linguistic stimuli generally are more often reported from the right ear.
- Specific sub-phonemic parameters of these stimuli- the transition time between the consonant and vowel in a CV syllable and VOT.
What did Cowell and Hugdhal (2000) investigate and what was their method?
Studied dichotic listening in 57 participants using CV syllables.
Conditions included a non-forced conditions (say what you hear the most clearly) a forced right condition and a forced left condition.
