Is Novelty Detection Important in Long-Term Odor Memory?

Abstract

Memory for odors is believed to be longer-lasting than memory for visual stimuli, as is evidenced by flat forgetting curves. However, performance on memory tasks is typically weaker in olfaction than vision. Studies of odor memory that use forced-choice methods confound responses that are a result of a trace memory and responses that can be obtained through process of elimination. Moreover, odor memory is typically measured with common stimuli, which are more familiar and responses may be confounded by verbal memory, and measure memory in intentional learning conditions, which are ecologically questionable. Here we demonstrate the value of using tests of memory in which hit rate and correct rejection rate are evaluated separately (i.e., not using forced-choice methods) and uncommon stimuli are used. This study compared memory for common and uncommon odors and pictures that were learned either intentionally (Exp. 1) or incidentally (Exp. 2) and tested with either a forced-choice or a one-stimulus-at-a-time (“monadic”) recognition task after delays of 15 min, 48 h or 1 week. As expected, memory declined with delay in most conditions, but depended upon the particular measure of memory and was better for pictures than odors and for common than uncommon stimuli. For common odors, hit rates decreased with delay but correct rejection rates remained constant with delay. For common pictures, we found the opposite result, constant hit rates and decreased correct rejection rates. Our results support the ‘misfit theory of conscious olfactory perception’, which highlights the importance of the detection of novelty in olfactory memory and suggests that olfactory memory should be studied using more ecologically valid methods.

Episodic memory and recognition are influenced by cues’ sensory modality: comparing odours, music and faces using virtual reality

“…The lower recognition score for odours than for other sensory cues confirmed our hypothesis. It is also in agreement with studies where the recognition of odours was compared to the recognition of other stimuli, such as faces (Cornell Kärnekull et al, 2015), environmental sounds (Cornell Karnekull et al, 2018) and common pictures (Cameron et al, 2021), even if no recognition memory performance differences were observed between odours and abstract simple shapes (Lawless, 1978). This reduced ability to recognize unidentifiable odours can be attributed to the difficulty of verbally categorising and communicating about odours (Jraissati & Deroy, 2021;Majid & Burenhult, 2014).…”

“…In this controlled experimental approach, episodic memory characteristics overlap with those observed in approaches focusing on autobiographical 4 memory (for reviews, Annett, 1996;Hackländer et al, 2018;Herz & Engen, 1996;Larsson et al, 2014;. While odours are less recognized than visual cues when presented among distractors (e.g., Cameron et al, 2021;Cornell Karnekull et al, 2015;Engen, 1987), they show similar strength to initiate the retrieval of previously associated items (paintings, numbers, pictures) than show visual, tactile, musical or verbal cues (Davis, 1977;Herz, 1998). However, the very limited number of studies urges to be cautious about conclusions about the uniqueness of odours as cues for episodic memory.…”

Episodic memory and recognition are influenced by cues’ sensory modality: Comparing odours, music and faces using virtual reality

“…The lower recognition score for odours than for other sensory cues confirmed our hypothesis. It is also in agreement with studies where the recognition of odours was compared to the recognition of other stimuli, such as faces (Cornell Kärnekull et al, 2015), environmental sounds (Cornell Karnekull et al, 2018) and common pictures (Cameron et al, 2021), even if no recognition memory performance differences were observed between odours and abstract simple shapes (Lawless, 1978). This reduced ability to recognize unidentifiable odours can be attributed to the difficulty of verbally categorising and communicating about odours (Jraissati & Deroy, 2021;Majid & Burenhult, 2014).…”

“…In this controlled experimental approach, episodic memory characteristics overlap with those observed in approaches focusing on autobiographical 4 memory (for reviews, Annett, 1996;Hackländer et al, 2018;Herz & Engen, 1996;Larsson et al, 2014;. While odours are less recognized than visual cues when presented among distractors (e.g., Cameron et al, 2021;Cornell Karnekull et al, 2015;Engen, 1987), they show similar strength to initiate the retrieval of previously associated items (paintings, numbers, pictures) than show visual, tactile, musical or verbal cues (Davis, 1977;Herz, 1998). However, the very limited number of studies urges to be cautious about conclusions about the uniqueness of odours as cues for episodic memory.…”