Hemispatial neglect (continued)
This condition is sometimes accompanied by a failure to report stimuli located in the contralesional
visual field when there is a competing stimulus in the ipsilesional field; this is called extinction. See
Attention 2 slide 21.
Balint's syndrome is another neuropsychological disorder that results in attentional dysfunctions. It
results from damge to both the right and the left parietal lobes. Patients with this disorder lose all
experience of space, can only see one object at a time, without being able to report where that object is
located or whether the object is moving toward or away from them.
The three main symptoms of Balint's syndrom (not all people with this disorder have all three
• Simultagnosia: Inability to perceive multiple objects.
• Optic ataxia: Problems controlling voluntary motor movements.
• Optic apraxia: Severe problems controlling voluntary eye movements.
What are the brain mechanisms that are involved in controlling attention?
1) What are the functional consequences of attention?
It increases the sensory processing of stimuli that are attended to in the processing areas that
correspond to them and diminishes the processing allocated to stimuli that are not being
2) What are the neural mechanisms that control those effects?
This depends on the mode of orienting. There are two distinct cortical networks that control
attention: the network controlling reflexive orienting and the one that controls volitional
orienting. Subcortical structures like the superior colliculus are implicated. The right
hemisphere controls most processes that have to do with attention, a good example of functional
specialization (mostly for reflexive attention). Volitional attention is controlled bilaterally.
Memory Traces and Schemas
The study of memory is the study of how we encode, retrieve, and retain past information, remember
both past and future information, and how we forget.
Hermann Ebbinghaus developped an experimental method with the objective of understanding how we
memorize meaningless, novel stimuli. He made up nonsense syllables (HUN VRAMAG ZOF GTA).
In his experiments, he varied the length of the list of nonsense stimuli, the retention interval, and the
type of memorization method. The curve resulting from his experiments is on slide 5 of the Memory
Trace power point. He established that memory can be studied experimentally, difficulty varies
disproportionately with list length, and the the amount of retention depends on the degree of initial
learning (levels of processing). He also showed that retention is better if studying is distributed over
Most metaphors attempting to describe memory do so in terms of physic