Recognition Memory Task Research Articles

Oscillations around memory

Neuroscience Hippocampal oscillations in the theta range have been hypothesized to play a central role in organizing neuronal ensembles to link together item and contextual representations. Experimental evidence in rodents shows the importance of theta oscillations for associative memory. However, the role of hippocampal theta oscillations in human memory is not as well understood. Kota et al. administered an associative recognition memory task to epilepsy patients who happened to have electroencephalogram electrodes implanted for other medical reasons. Theta oscillatory power increase in the 2- to 5-Hz range and phase reset in the hippocampus reflected processes supporting recollection, rather than familiarity, during encoding and retrieval. These observations link theta-range activity to associative memory encoding and retrieval in humans. J. Neurosci. 40 , 9507 (2020).

Evidence for an Age-Related Positivity Effect in Metacognitive Confidence Judgments

We examined age differences in metacognitive monitoring of emotionally-valenced stimuli. If older adults (OAs) are more focused on emotionally meaningful goals in late life (Carstensen, 2006), then they should demonstrate attentional and memory biases for positive stimuli over neutral and negative stimuli and, arguably, these cognitive biases should be reflected in their metacognitive judgments of learning. Judgments of learning (JOLs) for memory of positive, negative, and neutral words were collected. Younger adults (YAs) aged 18-23 years and OAs aged 65-90 years (N = 85) studied words in each valence category and made immediate JOLs, followed by a two-alternative forced choice (2AFC) recognition memory task. Analyses of JOLs revealed evidence for a positivity effect (Mather & Carstensen, 2005) in metacognitive confidence for OAs and an emotional salience effect in YAs (Tauber & Dunlosky, 2012; Zimmerman & Kelley, 2010). Predictably, YAs recognized more words than OAs, but valence did not affect number of words recognized and valence did not moderate age differences in recognition memory (p = .055). Memory monitoring as measured by resolution accuracy was equivalent in YAs and OAs (Hertzog & Dunlosky, 2011). Positive affect was higher and negative affect was lower in OAs relative to YAs (Gallant, Spaniol, & Yang, 2019), lending additional evidence to an orientation toward the positive in older adulthood. These results are novel in that they demonstrate an age-related positivity effect that extends beyond the domains of memory and emotion to the domain of metacognitive aging. Discussion will focus on theoretical, methodological, and applied implications.

Underdeveloped recollection during adolescence: Semantic elaboration and inhibition as underlying mechanisms

Recognition memory abilities undergo important developmental changes until adulthood, with earlier studies showing different trajectories for recollection and familiarity-based processes. However, previous work has primarily focused on childhood, and differences in memory retrieval, notably in recollection, between adolescents and adults, have been hard to confirm. To address this gap in the literature and to better characterize the development of recollection and familiarity during adolescence, we applied the process dissociation procedure to a word recognition memory task, after semantic and perceptual encoding of words, in adolescents (n = 30, 13–15 years of age) and young adults (n = 30, 20–22 years). Relative to young adults, adolescents’ lower recognition memory performance was restricted to context recollection of semantically encoded items. This effect was predicted by individual differences in inhibitory control abilities. These findings highlight the distinct developmental trajectories of familiarity and context recollection over the course of adolescence, and suggest that semantic elaboration and inhibition are two key mechanisms toward the full maturation of recollection processes.

Delayed voluntary physical exercise restores “when” and “where” object recognition memory after traumatic brain injury

Physical exercise has been associated with improved cognition and may even reduce memory deficits after brain injuries. The aims of this work were to: 1) assess whether voluntary physical exercise can reduce the deficits associated with traumatic brain injury (TBI) in two different components of episodic-like memory based on object recognition, temporal order memory (“when”), and object location memory (“where”); and 2) determine whether changes in levels of brain-derived neurotrophic factor (BDNF) in the hippocampus and prefrontal cortex, as well as alterations in hippocampal cytokines, insulin-like growth factor-1 (IGF-1) and vascular endothelial growth factor (VEGF), may influence the effects exercise has on either or both tasks. The rats were distributed into a sham group, a TBI group that remained sedentary (TBI-sed), and a TBI group that had access to a running wheel for a 25-day period from post-injury day 11 (TBI-exe). The rats were sacrificed after the “where” memory task, at post-injury day 37. Physical exercise restored the “when” and “where” memories, which had been impaired by the TBI, and increased the concentration of BDNF in the hippocampus, but not the prefrontal cortex. Neither TBI nor exercise were found to significantly affect hippocampal cytokines, IGF-1 or VEGF at this time post-injury. BDNF levels showed significant positive correlations with exercise, and with “when” (but not “where”) memory. These results indicate that post-injury physical exercise restores “when” and “where” object recognition memory tasks after TBI, and that increased BDNF seems to be involved in this effect, particularly with regard to “when” memory.

Exploring the Encoding Specificity Principle and Context-Dependent Recognition in Virtual Reality

A virtual reality (VR) training system’s effectiveness is determined by how well the knowledge-and skills-gained in the virtual environment transfers to real-world performance. The purpose of this study was to examine the efficacy of virtual reality training by comparing semantic memorization in congruent (e.g., memorization task in VR and recognition task in VR) versus incongruent environments (e.g., memorization task in VR and recognition task in the real word). In the present study, we semi replicated Godden and Baddeley’s 1980 study on context-dependent recognition memory by using a photorealistic virtual reality environment in place of the underwater, scuba environment. Results revealed participants that learned semantic information in the virtual environment performed highly on the memory recognition task in the material, real-world environment (and vice versa). These findings replicate and extend Godden and Baddeley’s original results and provide evidence for the use of VR training to support semantic-based knowledge transfer.

Associations of prenatal maternal stress with measures of cognition in 7.5-month-old infants.

Studies have shown that prenatal stress can negatively impact neurodevelopment, but little is known about its effect on early cognitive development. We assessed the impact of prenatal stress on cognition in 152 7.5-month-old infants using Cohen's Perceived Stress Scale (PSS), maternal telomere length (MTL), and a Stressful Life Events (SLE) Scale. A visual recognition memory task consisting of nine blocks, each with one familiarization trial (two identical stimuli) followed by two test trials (one familiar stimulus, one novel), was administered. Outcomes assessed included: average time looking at stimuli (measure: processing speed), time to reach looking time criterion (measure: attention), and the proportion of time looking at the novel stimulus (measure: recognition memory). We examined the association of each stress measure with each outcome adjusted for infant age and sex, which of the two stimuli in each set was novel, household income, and maternal age, education, and IQ. Higher prenatal stress was associated with shorter looking durations [PSS (β=-1.6, 95% CI: -2.5, -0.58); SLE (β=0.58, 95% CI: -0.08, 1.24); MTL (β=1.81, 95% CI: 0.18, 3.44)] and longer time to reach criterion [PSS (β=9.1, 95% CI: 1.6, 16.6); SLE (β=12.2, 95% CI: 1.9, 24.1); MTL (β=-23.1, 95% CI: -45.3, -0.9)], suggesting that higher prenatal stress is associated with decreased visual attention in infancy.

P.592 Predictors of suicidal ideation and preparative behaviours in subjects with bipolar disorder: the contribution of the chronobiological dis-rhythmicity

Several lines of evidence indicate that anesthetic doses of the non-competitive N-methyl-D-aspartate receptor antagonist ketamine disrupt memory functions in rodents. The mechanism by which anesthetic ketamine produces its adverse behavioural effects is not yet clarified. The implication of nicotinic acetylcholine receptor as a potential site of action of anesthetic ketamine adverse effects on memory is proposed. We investigated the ability of α4β2 nicotinic receptor agonist ABT-418 (0.01, 0.03, 0.1 mg/kg, i.p.) and α7 nicotinic receptor agonist GTS-21 (0.3, 1, 3 mg/kg, i.p.) to counteract recognition memory deficits produced by acute post-training administration of anesthetic ketamine (100 mg/kg, i.p.) in rats. For this purpose, the novel object recognition test, a behavioural paradigm assessing recognition memory abilities in rodents was used. Post-training acute administration of GTS-21 (3 mg/kg) counteracted anesthetic ketamine-induced performance deficits in the novel object recognition memory task. By contrast, ABT-418 failed to reverse the recognition memory deficits caused by anesthetic ketamine. The present findings propose that an α7 nicotinic receptor component might modulate anesthetic ketamine’s adverse effects on recognition memory.

Dopamine Related Genes Differentially Affect Declarative Long-Term Memory in Healthy Humans.

In humans, monetary reward can promote behavioral performance including response times, accuracy, and subsequent recognition memory. Recent studies have shown that the dopaminergic system plays an essential role here, but the link to interindividual differences remains unclear. To further investigate this issue, we focused on previously described polymorphisms of genes affecting dopaminergic neurotransmission: DAT1 40 base pair (bp), DAT1 30 bp, DRD4 48 bp, and cannabinoid receptor type 1 (CNR1). Specifically, 669 healthy humans participated in a delayed recognition memory paradigm on two consecutive days. On the first day, male vs. female faces served as cues predicting an immediate monetary reward upon correct button presses. Subsequently, participants performed a remember/know recognition memory task on the same day and 1 day later. As predicted, reward increased accuracy and accelerated response times, which were modulated by DAT 30 bp. However, reward did not promote subsequent recognition memory performance and there was no interaction with any genotype tested here. Importantly, there were differential effects of genotype on declarative long-term memory independent of reward: (a) DAT1 40 bp was linked to the quality of memory with a more pronounced difference between recollection and familiarity in the heterozygous and homozygous 10-R as compared to homozygous 9-R; (b) DAT1 30 bp was linked to memory decay, which was most pronounced in homozygous 4-R; (c) DRD4 48 bp was linked to overall recognition memory with higher performance in the short allele group; and (d) CNR1 was linked to overall memory with reduced performance in the homozygous short group. These findings give new insights into how polymorphisms, which are related to dopaminergic neuromodulation, differentially affect long-term recognition memory performance.

Associations of prenatal exposure to phthalates with measures of cognition in 7.5-month-old infants

Background: Phthalates are endocrine disrupting chemicals found in consumer products. Prenatal exposure has been associated with adverse neurobehavior, but little is known about the influence on infant cognition. Methods: A visual recognition memory task was used to assess cognition in 239 7.5-month-old infants (122 females; 117 males) from a prospective cohort study. Phthalate metabolites were quantified in maternal urine from 16-18 gestational weeks and a pool of five urines collected across pregnancy. The cognitive task included familiarization trials (infant shown 2 identical images/stimuli) and test trials (infant shown a familiar image/stimulus paired with a novel one). During familiarization trials, average time looking at stimuli before looking away (measure of processing speed), and time to reach looking time criterion (measure of attention) were assessed. During test trials, proportion of time looking at the novel stimulus (measure of recognition memory) was assessed. Associations of monoethyl phthalate (MEP), sum of di(2-ethylhexyl) phthalate metabolites (∑DEHP), and sum of di(isononyl) phthalate metabolites (∑DINP) with each outcome were assessed using generalized linear models adjusted for multiple potential confounders. Infant sex was considered a potential effect modifier. Results: Mothers were mostly white and college educated. Phthalate biomarker concentrations were consistent with the U.S. general population. Each interquartile range (IQR) increase of ∑DEHP at 16-18 weeks was associated with a 5.2-second (95%CI=1.8,8.6) increase in time to reach looking time criterion in males but not females. An IQR increase in ∑DINP in the pooled sample was associated with a 1.0% (95%CI=-1.8,-0.3) decrease in novelty preference across both sexes and similarly associated with 16-18 week ∑DINP. MEP was not associated with cognition. None of the phthalate biomarkers were associated with information processing speed. Conclusion: Prenatal exposure to DEHP may be associated with poorer visual attention in males and DINP with poorer recognition memory in both sexes. ES007326;ES022848;ES028607;RD83543401;OD023272.

Usefulness of familiarity signals during recognition depends on test format: Neurocognitive evidence for a core assumption of the CLS framework

Familiarity-based discrimination between studied items and similar foils in yes/no recognition memory tests is relatively poor. The complementary learning systems (CLS) framework explains this with the small difference in familiarity strength between targets and foils. The framework, however, also predicts that familiarity values of targets and corresponding similar foils are directly comparable – as long as they are presented side by side in a forced-choice corresponding (FCC) test. This is because in each trial, targets tend to be more familiar than their corresponding foils. In contrast, when forced-choice displays contain non-corresponding foils (FCNC) which are similar to other studied items, familiarity values are not directly comparable (as in yes/no-tasks). In a recognition memory task with pictures of objects, we found that the putative ERP correlate of familiarity, the mid-frontal old/new effect for targets vs. foils, was significantly larger in FCC compared to FCNC displays. Moreover, single-trial target-foil amplitude differences predicted the accuracy of the recognition judgment. This study supports the assumption of the CLS framework that the test format can influence the diagnostic reliability of familiarity. Moreover, it implies that the mid-frontal old/new effect does not reflect the difference in the familiarity signal between studied and non-studied items but the task-adequate assessment of this signal.

Rats recognize spatial and temporal attributes in a new object recognition memory task with multiple trials

BackgroundEpisodic-like memory tasks based on the spontaneous exploration of objects are commonly applied in one-trial protocols. However, multiple-trial designs are known to reduce animal numbers and data variance, providing faster accumulation of data. New methodIn this study, we devised a new object recognition memory task for rats that carry out multiple trials per session. We developed three types of continual trial tasks: a longer protocol, a shorter protocol, and a protocol in which the experimental session was divided into two days. ResultsIn our design, rats expressed temporal and spatial memory, but not what-where-when content integration. We found that shorter protocols were more efficient to evaluate memory capabilities. Comparison with existing methodsTo the best of our knowledge, it is the first object recognition task with multiple trials that simultaneously assess the temporal and spatial aspects of episodic-like memory. ConclusionsWe suggest that our task is suitable for the simultaneous measurements of brain functions related to spatial and temporal attributes in rats.

Neural correlates of verbal recognition memory in obese adults with and without major depressive disorder.

BackgroundObesity and major depressive disorder (MDD) independently contribute to memory impairment. Little is known about shared neural mechanisms that may result in the cognitive impairment experienced by these populations. This study's aim was to determine how obesity impacts neural activity during a verbal recognition memory task in individuals both with and without MDD.MethodsFunctional magnetic resonance imaging was employed to examine whether differences in neural activation patterns would be seen across three groups during the Warrington's Recognition Memory Test. Three study groups are reported: 20 subjects with obesity but without MDD (bariatric controls), 23 subjects with past or current MDD and obesity, and 20 normal BMI controls (healthy controls).ResultsThree‐group conjunction analyses indicated that overlapping neural regions were activated during both encoding and retrieval processes across all groups. However, second‐level 2‐group t‐contrasts indicated that neural activation patterns differed when comparing healthy and bariatric controls, and when comparing bariatric controls and bariatric MDD participants.DiscussionResults indicate that obesity in conjunction with MDD confers a subtle impact on neural functioning. Given high rates of obesity and MDD comorbidity, and the role of cognition on ability to return to premorbid level of functioning, this association should inform treatment decisions.

Behavioral changes and gene profile alterations after chronic 1,950-MHz radiofrequency exposure: An observation in C57BL/6 mice.

IntroductionDue to public concerns about deleterious biological consequences of radiofrequency electromagnetic fields (RF‐EMF), the potential effects of RF‐EMF on the central nervous system have received wide consideration.MethodsHere, two groups of C57BL/6 mice, aged 2 and 12 months, were exposed to 1,950‐MHz RF‐EMF at a specific absorption rate of 5.0 W/kg for chronic periods (2 hr/day and 5 days/week for 8 months). Behavioral changes were then assessed in the mice at 10 months (sham‐ or RF‐10M) and 20 months (sham‐ or RF‐20M), on the open‐field test, the Y‐maze test, and an object recognition memory task, while biological effects were analyzed via microarray gene profiling of the hippocampus.ResultsOpen‐field test results showed a decrease in the time duration spent at the center while there was a decrease in enhanced memory shown by the Y‐maze test and the novel object recognition test in the RF‐20M mice, compared to sham‐exposed mice, but no significant changes in the RF‐10M group. Based on a 2‐fold change cutoff, the microarray data revealed that 15 genes, which are listed as being involved in neurogenesis on Gene Ontology, were altered in both groups. Quantitative real‐time PCR for validation showed increased expression of Epha8 and Wnt6 in the hippocampi of RF‐20M group mice, although 13 additional genes showed no significant changes following RF‐EMF exposure.ConclusionTherefore, cognitive enhancement following chronic exposure for 8 months to RF‐EMF from middle age may be associated with increases in neurogenesis‐related signals in the hippocampus of C57BL/6 mice.

Naming guides how 12-month-old infants encode and remember objects

A foundation of human cognition is the flexibility with which we can represent any object as either a unique individual (my dog Fred) or a member of an object category (dog, animal). This conceptual flexibility is supported by language; the way we name an object is instrumental to our construal of that object as an individual or a category member. Evidence from a new recognition memory task reveals that infants are sensitive to this principled link between naming and object representation by age 12 mo. During training, all infants (n = 77) viewed four distinct objects from the same object category, each introduced in conjunction with either the same novel noun (Consistent Name condition), a distinct novel noun for each object (Distinct Names condition), or the same sine-wave tone sequence (Consistent Tone condition). At test, infants saw each training object again, presented in silence along with a new object from the same category. Infants in the Consistent Name condition showed poor recognition memory at test, suggesting that consistently applied names focused them primarily on commonalities among the named objects at the expense of distinctions among them. Infants in the Distinct Names condition recognized three of the four objects, suggesting that applying distinct names enhanced infants' encoding of the distinctions among the objects. Infants in the control Consistent Tone condition recognized only the object they had most recently seen. Thus, even for infants just beginning to speak their first words, the way in which an object is named guides infants' encoding, representation, and memory for that object.

Test–retest reliability of RC21X: a web-based cognitive and neuromotor performance measurement tool

As computerized cognitive testing becomes increasingly popular in clinical and research settings, conducting studies on efficacy and psychometric properties is essential. One such program is RC21X, a web-based brain performance measurement tool. Based on empirically supported neurocognitive and neuromotor tasks, the 12-min test consists of 15 modules measuring memory, motor coordination, processing speed, and executive functioning. Because individuals may use RC21X repeatedly to track changes in cognitive performance, establishing reliability of the program is imperative. The current study examined test-retest reliability of RC21X within a 2-week period. The sample consisted of 222 individuals: 192 (86.5%) were male, and 30 (13.5%) were female. Average age was 44.06years (SD=17.76), with ages ranging from 7 to 82years. We computed Pearson's correlation coefficients for module and composite scores to determine reliability between performance at times 1 and 2. All correlations were statistically significant (p<.001). The 2-week test-retest reliability for composite score was 0.72, with subtest coefficients ranging from 0.54 on an auditory memory recognition task to 0.89 on a finger tapping task. We replicated these analyses with participants' (n=43) test sessions 3 and 4; we found similar results to those from test 1 and test 2 analyses, suggesting stability of results over multiple administrations. Results for RC21X were comparable to existing literature that supports moderate to high reliability of other computer-based tests. Although future research needs to investigate validity of RC21X, our findings support potential applications in research, clinical use, and personal brain performance measurement.

Contextual source information modulates neural face processing in the absence of conscious recognition: A threat-of-shock study

Often the source of information is as important as the information itself. The present study examined the impact of contextual threat and safety signals (source information) on memory encoding and recognition of faces (item information). In two experimental sessions, 30 participants viewed neutral face pictures. In the encoding session, 60 faces were presented with contextual background colors (blue or green, 30 pictures each) which were verbally instructed to signal either threat-of-shock or safety. In the recognition session, the 60 old faces intermixed with 30 new faces were shown while a combined old/new recognition and source memory task was performed. During the encoding session, face processing varied as a function of contextual source information. Confirming successful threat-of-shock manipulation, threatening compared to safe face–context compounds revealed differential neural processing (early parieto-occipital and late fronto-central negativity) as well as pronounced threat ratings. During the recognition session, participants had serious problems identifying old from new faces with poor source memory. Intriguingly, however, brain activity differentiated previously seen faces from newly presented pictures (old/new ERP effect). Moreover, old faces presented within a threat context were associated with distributed late negativities compared to old safe faces. Thus, threat effects not only emerged during face encoding (incidental learning) but also during face recognition, although no valid judgements could be made regarding the threatening or safe sources. These findings support the notion that contextual source information critically modulates person perception and recognition as a form of an expectation based remembering in the absence of conscious recognition.

Assessing Rhythmic Visual Entrainment and Reinstatement of Brain Oscillations to Modulate Memory Performance.

The human brain’s ability to store information and remember past events is thought to be orchestrated by the synchronization of neuronal oscillations in various frequency bands. A vast amount of research has found that neural oscillations in the theta (∼4–7 Hz) and alpha (∼8–12 Hz) bands play an important role in memory formation. More specifically, it has been suggested that memory performance benefits if the same oscillatory pattern is present during encoding and retrieval. However, the causal relevance of these oscillations is not well understood. Rhythmic sensory stimulation is thought to entrain ongoing brain oscillations and modulate associated functions (e.g., memory formation). In the present study, we used rhythmic visual stimulation at 6 and 10 Hz to experimentally modulate the memory encoding process in a recognition memory task. In addition, we reinstated oscillatory activity from the encoding episode during retrieval, which has been hypothesized to result in memory performance improvements compared to non-reinstated conditions and incongruent reinstatement. Contrary to our hypothesis, we find no effect of neural entrainment during encoding on subsequent memory performance. Likewise, memory retrieval does not benefit from neural reinstatement. The results are discussed with respect to methodological challenges of rhythmic sensory stimulation as a means to alter cognitive processes and induce context-dependent memory effects.

Transcutaneous Vagus Nerve Stimulation (tVNS) Improves High-Confidence Recognition Memory but Not Emotional Word Processing.

Previous clinical research found that invasive vagus nerve stimulation (VNS) enhanced word recognition memory in epileptic patients, an effect assumed to be related to the activation of brainstem arousal systems. In this study, we applied non-invasive transcutaneous auricular VNS (tVNS) to replicate and extend the previous work. Using a single-blind, randomized, between-subject design, 60 healthy volunteers received active or sham stimulation during a lexical decision task, in which emotional and neutral stimuli were classified as words or non-words. In a subsequent recognition memory task (1 day after stimulation), participants' memory performance on these words and their subjective memory confidence were tested. Salivary alpha-amylase (sAA) levels, a putative indirect measure of central noradrenergic activation, were also measured before and after stimulation. During encoding, pleasant words were more accurately detected than neutral and unpleasant words. However, no tVNS effects were observed on task performance or on overall sAA level changes. tVNS also did not modulate overall recognition memory, which was particularly enhanced for pleasant emotional words. However, when hit rates were split based on confidence ratings reflecting familiarity- and recollection-based memory, higher recollection-based memory performance (irrespective of emotional category) was observed during active stimulation than during sham stimulation. To summarize, we replicated prior findings of enhanced processing and memory for emotional (pleasant) words. Whereas tVNS showed no effects on word processing, subtle effects on recollection-based memory performance emerged, which may indicate that tVNS facilitates hippocampus-mediated consolidation processes.

An associative analysis of recognition memory: Relative recency effects in an eye-tracking paradigm.

We report 2 eye-tracking experiments with human variants of 2 rodent recognition memory tasks, relative recency and object-in-place. In Experiment 1 participants were sequentially exposed to 2 images, A then B, presented on a computer display. When subsequently tested with both images, participants biased looking toward the first-presented image A: the relative recency effect. When contextual stimuli x and y, respectively, accompanied A and B in the exposure phase (xA, yB), the recency effect was greater when y was present at test, than when x was present. In Experiment 2 participants viewed 2 identical presentations of a 4-image array, ABCD, followed by a test with the same array, but in which one of the pairs of stimuli exchanged position (BACD or ABDC). Participants looked preferentially at the displaced stimulus pair: the object-in-place effect. Three further conditions replicated Experiment 1’s findings: 2 pairs of images were presented one after the other (AB followed by CD); on a test with AB and CD, relative recency was again evident as preferential looking at AB. Moreover, this effect was greater when the positions of the first-presented A and B were exchanged between exposure and test (BACD), compared with when the positions of second-presented C and D were exchanged (ABDC). The results were interpreted within the theoretical framework of the Sometime Opponent Process model of associative learning (Wagner, 1981).

Developmental onset distinguishes three types of spontaneous recognition memory in mice

Spontaneous recognition memory tasks build on an animal’s natural preference for novelty to assess the what, where and when components of episodic memory. Their simplicity, ethological relevance and cross-species adaptability make them extremely useful to study the physiology and pathology of memory. Recognition memory deficits are common in rodent models of neurodevelopmental disorders, and yet very little is known about the expression of spontaneous recognition memory in young rodents. This is exacerbated by the paucity of data on the developmental onset of recognition memory in mice, a major animal model of disease. To address this, we characterized the ontogeny of three types of spontaneous recognition memory in mice: object location, novel object recognition and temporal order recognition. We found that object location is the first to emerge, at postnatal day (P)21. This was followed by novel object recognition (24 h delay), at P25. Temporal order recognition was the last to emerge, at P28. Elucidating the developmental expression of recognition memory in mice is critical to improving our understanding of the ontogeny of episodic memory, and establishes a necessary blueprint to apply these tasks to probe cognitive deficits at clinically relevant time points in animal models of developmental disorders.