The Memory and Forgetting Lab, headed by Dr. Talya Sadeh, investigates the neurocognitive mechanisms underlying Episodic Memory. The term episodic memory was coined in 1972 by the influential memory researcher, Endel Tulving, and is often described as (the perhaps uniquely human) capacity to mentally go back in time and relive events from our past (e.g., your 16th birthday or even yesterday's lunch).
Some of the major questions our lab explores are:
Why do we forget things we once remembered?
One possibility is that forgetting occurs because, like colours that fade, memories decay over time. Another possibility is that similar memories interfere with one another; for instance, we are more likely to forget the faces of the students in class if subsequently we encounter many other students. For years scholars have attempted to adjudicate between these two possibilities, lacking a unifying account of forgetting. With my colleagues, I have proposed the Representation Theory of Forgetting, according to which forgetting can occur due to decay or due to interference, depending on the type of memory. For both anatomical and cognitive reasons, we hypothesized and have shown that:
- Recollection-based memories, supported by the hippocampus, are represented in orthogonal patterns and, therefore, are relatively resistant to interference from each other. However, these memories are sensitive to decay.
- Familiarity-based memories, supported by extra-hipocampal structures, are not represented in orthogonal patterns and, therefore, are sensitive to interference.
Is memory affected not only by post-learning processes (e.g., decay and interference), but also by processes that occur prior to learning?
Yes, it is! This exciting idea stems from rodent studies showing that spontaneous neural activity prior to exposure to new information is reinstated during successful learning. We are now looking at this idea in humans.
What processes drive recall memory?
Recall tests (such as 'open question' tests), are largely assumed to rely only and invariably on a contextual, hippocampal-driven process. My research has challenged this assumption and has provided evidence for the psychological reality of a familiarity-like, non-hippocampal process in recall. Intuitively, this process may be best described as the experience of a piece of information, such as a sentence we once heard, "just popping into the mind", with no information available regarding the context of that sentence.
This research is not only of theoretical importance, but also provides some practical potential for alleviation of memory decline. Most common memory-disorders (e.g., Alzheimer's disease, Mild Cognitive Impairment and even memory decline due to aging) are associated with increased cell-loss in the hippocampus, and consequently deficits in recollection. One exciting idea is that by using mnemonic strategies which capitalize on this familiarity-like process, individuals with memory disorders or decline may show improved performance in tests of recall (in which they typically perform badly at).
Remembering Alone and Together - Autonoetic and Socionoetic consciousness
How does social interaction shape episodic memory?
The influential memory researcher Endel Tulving maintained that a necessary correlate of episodic memory is autonoetic (self-knowing) consciousness which "confers the special phenomenal flavour to the remembering of past events, the flavour that distinguishes remembering from other kinds of awareness, such as [...] perceiving, thinking, imagining or dreaming."
In a collaborative and interdisciplinary effort, we have begun investigating the notion that episodic memory and its correlate, autonoetic consciousness, play a crucial-and underappreciated-role not only in forming a sense of self and identity but also in social exchange. Perhaps the primary functionality of autonoesis in social communication is to allow both the rememberer and his/her audience to jointly re-experience the past. This joint projection into the past - which we term socionoetic consciousness - forms a unique and strong basis for connections between individuals, and also imbues the joint memory with a distinct form of epistemic authority.
My approach is to let the ideas and questions determine the tools. Cognitive neuroscientists have a constantly increasing set of technologies and methods at their disposal, such as:
- Behavioural experiments
- Neuroimaging (e.g., Functional magnetic resonance imaging; fMRI, EEG and MEG)
- Neurostimulators (TMS, tDCS)
- Physiological measurements (e.g., eye-tracking)
- Research of various populations (amnesic patients, older adults, children)
- Other methods are available through collaborations in BGU and abroad (e.g., animal research, computational modelling).