scholarly journals Visual Discrimination Accuracy across Reaction Time in Rats

2020 ◽  
Vol 7 (1) ◽  
pp. 23-38 ◽  
Author(s):  
Daniel Kurylo ◽  
Cindy Lin
Keyword(s):  
Reaction Time ◽  
Visual Discrimination ◽  
Discrimination Accuracy

Visual Discrimination Learning in Monkeys with Bilateral Parietal Cortex Lesions

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 131-131
Author(s):  
K N Dudkin ◽  
I V Chueva ◽  
F N Makarov ◽  
I V Orlov
Keyword(s):  
Reaction Time ◽  
Discrimination Learning ◽  
Parietal Cortex ◽  
Learning Process ◽  
Visual Discrimination ◽  
Spatial Relationships ◽  
Motor Reaction ◽  
Visual Discrimination Learning ◽  
Visual Attributes ◽  
Area 7

The characteristics of visual discrimination learning were tested on rhesus monkeys during elaboration of an instrumental reflex after bilateral extirpation of the parietal cortex area 7. The animals were trained to discriminate stimuli with different visual attributes (shape, colour, orientation, size, spatial relationships). Their decisions and motor reaction times were recorded. Bilateral extirpation of area 7 did not influence learning characteristics for shape and colour discrimination. The duration of the learning process and the motor reaction time were shortest with these visual attributes. When monkeys were required to discriminate geometrical figures of different orientations and size, these learning characteristics slightly increased. However, learning to discriminate spatial relationships was dramatically impaired. As a result, the duration of the learning process and motor reaction time significantly increased and the level of correct decisions after training significantly decreased. Visual stimuli associated with identical learning characteristics formed distinct groups in a cluster analysis. These results support the suggestion that area 7 is a structural and functional component of mechanisms involved in evaluation of spatial relationships. The impairment of the learning to discriminate spatial relationships can be explained by a change of learning strategy upon disturbance of this mechanism, associated with visual-vestibular interactions and synchronisation processes which bind distributed neurons across different cortical areas into synchronised assemblies.

scholarly journals Weber’s law is the result of exact temporal accumulation of evidence

2018 ◽  
Author(s):  
Jose L. Pardo-Vazquez ◽  
Juan Castiñeiras ◽  
Mafalda Valente ◽  
Tiago Costa ◽  
Alfonso Renart
Keyword(s):  
Reaction Time ◽  
Broad Class ◽  
Sequential Sampling ◽  
Behavioral Effect ◽  
Just Noticeable Difference ◽  
Weber’S Law ◽  
Discrimination Accuracy ◽  
Weber's Law ◽  
Evidence Accumulation ◽  
Hard Limit

AbstractWeber’s law states that the discriminability between two stimulus intensities depends only on their ratio. Despite its status as the cornerstone of psychophysics, the mecha-nisms underlying Weber’s law are still debated, as no principled way exists to choose between its many proposed alternative explanations. We studied this problem training rats to discriminate the lateralization of sounds of different overall level. We found that the rats’ discrimination accuracy in this task is level-invariant, consistent with Weber’s law. Surprisingly, the shape of the reaction time distributions is also level-invariant, implying that the only behavioral effect of changes in the overall level of the sounds is a uniform scaling of time. Furthermore, we demonstrate that Weber’s law breaks down if the stimulus duration is capped at values shorter than the typical reaction time. Together, these facts suggest that Weber’s law is associated to a process of bounded evidence accumulation. Consistent with this hypothesis, we show that, among a broad class of sequential sampling models, the only robust mechanism consistent with reaction time scale-invariance is based on perfect accumulation of evidence up to a constant bound, Poisson-like statistics, and a power-law encoding of stimulus intensity. Fits of a minimal diffusion model with these characteristics describe the rats performance and reaction time distributions with virtually no error. Various manipulations of motivation were unable to alter the rats’ psychometric function, demonstrating the stability of the just-noticeable-difference and suggesting that, at least under some conditions, the bound for evidence accumulation can set a hard limit on discrimination accuracy. Our results establish the mechanistic foundation of the process of intensity discrimination and clarify the factors that limit the precision of sensory systems.

Sign in / Sign up

Export Citation Format

Share Document