1. Simple attention model in emergent
Posner cueing task

3. (Dedrick & Trick, 2009)

8. In this model network's object recognition capacities are viewed as a function of the spatial distribution of two objects.

9. How deos it look like in network model?
Different object features + different location
Same object feature + diff. location
3. Diff. Object feature same location
Different objects in different places (1 – dorsal and ventral) are harder to recognize than same object feature on different places(2 - dorsal). Objects which are overlaping (3) are more difficult to recognize (dorsal do not help ventral and ventral demands more on attention).
How deos it look like in network model?

10. Where is parallel with Posner cueing test ???
First object feature (cue)
Second object feature (target)
Where is parallel with Posner cueing test ???

11. Emergent – conectivity of layers (show it now Ondro!!!)
SimpleAttnNet „r.wt“
- First
- Second
Third (less distinctive features – systems interfere)

12. Typical reaction times (young adults)PCT roughly:
In order to fit behavioral to model we should add a constant offset of roughly 310 ms to the number of cycles of settling for each trial.
Also that one cycle of settling in the network corresponds with one millisecond of processing in humans and that is not automatic -- adjusted time constant for activation updating (dt.vm_tau = 7 instead of the default of 3.3).
neutral
valid
invalid
Slowing factor
370ms
350ms
390ms
20ms

13. Effects of Spatial Pathway Strength
Spat_Obj_wt_scale (from 2 to 1)
V1_Spat_wt_scale (the lower the more cycle it takes to settle)
Close Posner and Retinal Eccentricity
Input data – ClosePosner
„the closer they are the lower slowing factor we observe“

14. Effects of Spatial Pathway Lesions
Hemispatial neglect patients
Disengaging attention problems (dissengaging theory of Posner at al.)
Patients are slower when the cue is presented on the side of space processed by the intact hemisphere (i.e., ipsilateral to the lesion), and the target is then processed by the lesioned hemisphere.

15. input_data - StdPosner
Lesion lay – NO_Lesion and then Lesion lay – SPAT1_2
lesion_locations and lesion_n_units are set to HALF
Check back 2 units on the right for Spat1 and Spat2

16. neutral, 370 ms
valid 350 ms
invalid 390 ms
(350/370) = 0,95
390*0,95= 307,5
Slowing factor is impact and remain same (cca 0,95)
But this does not apply for hemispatial lession patients where invalid trial in Posner cueing task. In that case slowing factor

17. Reverse Posner and hemispatial neglect patients
Input data – ReversePosner
Lession lay – SPAT1_2 – lession button and run
What will happen?
No interference WHAT - WHERE occurs.
dissengaging theory = „where is lesion there is greater slowing factor“

18. Balint's Syndrome Bilateral parietal lesions patients
Simultanagnosia - inability of an individual to perceive more than a single object at a time
Ventral simultanagnosia
Dorsal simultanagnosia

19. input_data - StdPosner
lesion_locations - FULL
lesion_n_units - HALF
Lesion button
It does not fit to disengage theory of Posner et al.
Why?
Disengage theory would instead predict bilateral slowing for invalid trials (i.e., difficulty disengaging)

20. lesion_locations - HALF
lesion_n_units - FULL
Lesion
input_data - MultiObj 
input_data – StdPosner

21. input_data - ReversePosner 
Attentional effect will be eliminated in all three conditions
Target presented to the good side of space has no difficulty competing with the weak residual representation of the cue in the damaged side.
Competition can explain the general tendency for neglect on the grounds that it is very rare to actually have no other competing stimuli (which can be relatively weak and still win the competition), coming into the intact side of space, so that attention is usually focused on the intact side.

22. Temporal Dynamics and Inhibition of Return
Cue activation persists to the point of target onset. (100ms delay in behavioral studies)
What if delay is longer??
„Inhibition of return“.
Inhibits the system from returning attention to the cued location after a sufficient delay.
Cue activated for long enough = spatial representations will become fatigued. If attention is subsequently directed there, the network will respond slower.

23. lesion_lay - NO_LESION
Input_data - StdPosner.
Then, click on kna_adapt_on in ControlPanel
Choose a cue duration and set cue_dur - 50
Valid-invalid difference decreases progressively with increasing duration 

24. Thank you 