Abstract
In order to capture autobiographical memory, inspired by the development of human intelligence, a computational AM model for autobiographical memory is proposed in this paper, which is a three-layer network structure, in which the bottom layer encodes the event-specific knowledge comprising 5W1H, and provides retrieval clues to the middle layer, encodes the related events, and the top layer encodes the event set. According to the bottom-up memory search process, the corresponding events and event sets can be identified in the middle layer and the top layer respectively; At the same time, AM model can simulate human memory roaming through the process of rule-based memory retrieval. The computational AM model proposed in this paper not only has robust and flexible memory retrieval, but also has better response performance to noisy memory retrieval cues than the commonly used memory retrieval model based on keyword query method, and can also imitate the roaming phenomenon in memory.
Introduction
Cognitive model is an important research direction in the field of artificial intelligence, of which autobiographical memory (AM) is a system which encodes, stores, and guides the retrieval of all remembered set information related to people’s personal experiences [1]. Although AM is an important part of thinking way, there are few modeling studies on it in China, such as encoding, retrieving and roaming through memories. Memory, usually considered as a function of AM, plays a vital role in self-acceptance and self-change. Roaming in memory refers to recalling a series of related AMs which span different life events, which is also the basis of memory therapy, usually used for the elderly to improve their psychological and cognitive health [2].
Remembered set memory and AM refer to the memory set of past events experienced by a person. However, the latter can be regarded as a special type of remembered set memory, which contains a person’s life experience from an individual point of view. Nevertheless, most existing computational remembered sets and AM modules do not differ significantly in their use and presentation.
Memory module is an important part of various cognitive models. For example, the cognitive models proposed in the references [3, 4, 5, 6] include both short-term working memory module and long-term memory module, which may not specify the exact type of long-term memory module used, such as remembered set [7], semantics [8] or autobiography [9]. The specific model in reference [10] explicitly describes a combination of remembered set memory modules. In the reference [11], a memory model for computing remembered sets is proposed, which is independent of other cognitive modules, and clearly defines the formation, retrieval and forgetting of past events in computer games. However, the use of this model is limited to the recall of historical data, and does not contain emotions [12] as one of the input fields, which is an important element in AM. The AM model named Xapagy proposed in the reference [13] is designed to realize narrative reasoning, and its activities are roughly similar to some psychological processes shown by human beings in stories. Xapagy uses complex natural language processing methods limited to storytelling. An online system is developed in the reference [14] that enables users to construct visual memories based on their mobile data as a form of visual AM for self-reflection and experience sharing. In the reference [15], the interaction between human and robot is stored as AM, so that the humanoid robot can accumulate experience and extract the regularity. However, when retrieving the stored memory, the aforementioned AM models only use the minimum amount of index knowledge to call a simple retrieval only for all the memories, all the memories of specific users, or all the memories that constitute the selected verbs. a computational AM model based on keyword query and used in the reference [16] for memory retrieval.
There is little research on roaming phenomenon in the literature about remembered set memory and AM model. In the reference [17, 18], an attempt was made to use the self-trapping attractor neural network to simulate the roaming effect in short-term and long-term associative memory. They refer to roaming in networks as a mechanism that allows “sparsely connected networks to wander around attractors far away from their initial state”.
Different from the aforementioned computational AM models, the computational AM model proposed in this paper aims to capture memory, including a picture snapshot of a person’s life experience and the related background, i.e., time, place, character, activity and emotion. It can use different types of cues to retrieve the encoded AM, and simulate the roaming phenomenon of human thinking in memory [19].
Autobiographical memory refers to the mixed memory of a person’s complex life events, which is closely related to the self-experience of memory. In the field of memory, research related to the self has a long history. Of course, the early psychologists did not clearly define the category of autobiographical memory, but only involved this field in the discussion of memory theory [20].
Deep learning is to learn the internal laws and representation levels of sample data. The information obtained in the learning process is of great help to the interpretation of data such as text, images and sounds. Its ultimate goal is to enable machines to have the ability to analyze and learn like humans, and to recognize data such as text, images, and sounds. Deep learning is a complex machine learning algorithm that has achieved results in speech and image recognition far surpassing previous related technologies [21].
AM model and its function realization
Psychological basis of AM model
In various AM models established by psychologists, the AM knowledge is divided into three levels, namely, life cycle, ordinary events and event-specific knowledge, from ordinary to specific, as shown in Fig. 1. If the cue is specific and personal, AM can be accessed directly, and if the cue is ordinary, a retrieval process must be generated to get more specific cues of related memory retrieval. The main difference between direct retrieval and generative retrieval is that the control process in generative retrieval adjusts the retrieval process, and the difference between these two memory retrieval methods is supported by neuroimaging evidence.
Schematic diagram of hierarchical structure of AM.
As shown in Fig. 2, the network architecture of AM model proposed in this paper is a top-down three-layer network structure, in which the
The AM model proposed in this paper adopts the dynamic nature of self-organizing network, in which the bottom layer encodes event-specific knowledge, which consists of 5W1H, the bottom layer provides retrieval clues, the middle layer associates event specific knowledge and encodes events. According to the bottom-up memory search procedure, the corresponding events and remembered sets can be identified in the middle layer and the top layer respectively.
With reference to the
Network architecture of AM model proposed in this paper.
Weight vector: Let
where the fuzzy AND operation “
If any vigilance constraint is violated, a mismatch reset occurs, in which
In the AM model (see Fig. 2), the input fields in
The
Coding and retrieval of remembered sets
Assuming that the related events of a remembered set occur at
The
Roaming in memory
In the AM model proposed in this paper, roaming refers to the mode of rule memory search.
In this section, how to make AM model roam in memory is proposed. Roaming includes two main processes, namely, using changing cues at each iteration, changing search cues and iteratively searching AM.
In Algorithm 3, the pseudo-code of changing the process of searching cues is given, which is similar in concept to chromosome variation in genetic algorithm [14]. The change process is summarized as adding adjusted noise to a given search cue consciously at a randomly determined position, regulated by following parameters, namely, the variation rate
In Algorithm 4, the pseudo-code of AM model roaming in memory is given. The roaming process is summarized as follows: based on the given memory search cues at the beginning of each iteration, the most relevant events are retrieved by using the given cues, which are not included in but will be added to the retrieved remembered set, and then the next iteration is carried out by using the changed retrieval cues. The termination rule of Algorithm 4 is to retrieve a predetermined number of events
Experimental results and discussion
A set of data was collected for the experiment, which consisted of 53 event snapshots of Ding Junhui, the champion of billiards in China, and the corresponding background [19]. The 53 events consisted of 12 event sets, each containing 3 to 7 events. All features except emotion were extracted directly from online web pages, and emotion was extracted manually from pictures and their backgrounds.
Based on the collected data set, eight types of relationships were defined, namely, strangers, colleagues, friends, acquaintances spouses, neighbors, family and classmates, and 15 types of activities were also defined, namely, catering, leisure, tourism, vacations, shopping, night outings, entertainment, sports, exercise, work, parties, socializing, celebrations, weddings and schools. After standardizing the input vectors, samples data were submitted to the AM model for encoding 53 events in
The listed in Table 1. Most of them adopt standard parameter values and do not need to be adjusted in the experiments.
List of AM-parameters used in the experiment
List of AM-parameters used in the experiment
After the AM model encodes the memory, the performance of memory retrieval was first tested using the following three types of cues:
Exact cues: An event was arbitrarily selected from the data set and its representation vector Partial cue: In a partial cue Noisy cue: In the selected
As a benchmark, a keyword-based query approach was selected. A set of events will be retrieved after executing a keyword-based query to respond to a given search cue. If the event that was originally used to generate the given cue can be found in the search set, the search is considered to be successful; Otherwise, it is considered to be failed.
The vigilance parameter
Since the criteria of generating partial cues and calculating successful retrieval were adopted, both the AM model and the keyword-based query method in this paper achieved 100% success rates in response to both exact and partial retrieval cues. But it is challenging when dealing with noisy cues because uncertainty, while well handled by the human brain, is not necessarily handled by many computational models. Figure 3 shows the query method for memory retrieval response of noisy cues with different percentages of cue integrity
Naming conventions for setting experimental parameters
Partial subsequences of AM retrieved by AM model (W22) during roaming
The success rate of memory retrieval using AM model and keyword-based query methods for response to noisy cues.
According to Fig. 3, when
The comparison of Fig. 3 shows that the AM model in this paper obviously performs preferably in the successful search rate of response to noisy cues compared with the keyword-based query method, because it can preferably deal with the uncertainty in the retrieval process by reducing the vigilance value when dealing with noisy cues. Thus, in dealing with incomplete information, the AM model in this paper is more inclined to pursue human intelligence.
In order to test the roaming performance of AM model in memory, different combinations of change rate
Table 3 shows some memory sequences retrieved by AM model during W22 configuration roaming process, as shown in Fig. 4 illustrates the roaming of AM model in this paper from set 5 (including 5 events) to set 10 (including 7 events), but roaming back to set 5 after 2 steps.
Image playback of events retrieved in the order shown in Table 3.
Therefore, the AM model in this paper can effectively retrieve a modest subset of a person’s AM and can model the roaming in memory.
This paper proposes a computational model AM for autobiographical memory encoding and retrieval in online autonomous subjects that model the life experience of users. It is a three-layer network structure model that can imitate the mental wandering phenomenon in human autobiographical memory; For the memory retrieval of noisy clues, the performance of the AM model proposed in this paper is better than the keyword-based query method, because the latter cannot handle many existing photos or noisy clues in the memory repository; The AM proposed in this paper can also realize the function of roaming in memories, it can imitate a person’s memory sequence before and after different sets of events, that is, a moderate subset of a person’s autobiographical memory, and can imitate the phenomenon of roaming in memories.
Footnotes
Funding
Key project of natural science research in Colleges and universities of Anhui Province (KJ2018A0881); Bozhou “Artificial Intelligence
