Zone Preference in the Visual Water Maze
June 26, 2025
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Hygrometers are precise scientific instruments used to measure humidity, also referred to as psychrometers and humidity sensors. Note that hygrometers measure relative humidity (%), which is the amount of vapor in the air compared to the highest possible amount. Absolute humidity, on the other hand, is the amount of vapor in a certain unit volume of air at a given temperature (e.g., g/m3).
Measuring humidity or water vapor in the air, soil, and confined space is essential. Inappropriate humidity levels in buildings, for example, can lead to poor environmental health and storage conditions. In fact, high humidity levels may lead to home pollutants, mold, and viruses, while low levels may cause skin irritation, electrostatic discharge, and breathing problems. Hygrometers are also used in industrial settings, manufacturing, greenhouses, museums, wine cellars, and cigar warehouses.
Hygrometers can be employed in a variety of settings, such as education, manufacturing, medical settings, and research. Thus, it’s no surprise that such instruments come in all shapes and sizes. Interestingly, the design of hygrometers has evolved significantly over the years. Note that it was in the 15th century when Leonardo da Vinci invented the first hygrometer.
While the majority of modern hygrometers use a material that attracts moisture and changes depending on how hydrated it is, there are different types of humidity measuring devices. Weather houses, for example, are old twisted-fiber hygrometers in which two figurines mounted on a turntable take turns coming out of a door, depending on how wet or dry the air is. Other mechanical hygrometers also use fiber material, such as human hair. To measure the amount of moisture, however, more advanced units are needed. The psychrometer, for example, consists of a pair of thermometers (with a wet and a dry bulb, respectively); depending on the evaporation and the temperature difference between the meters, one can measure the relative humidity in the air. Electronic hygrometers, on the other hand, facilitate readings; they can measure either capacitance or resistance and calculate humidity. Note that capacitive units consist of two metal plates and assess the ability of these plates to store a static electric charge, whereas resistive meters measure the electric current flow through ceramic material exposed to the air. There are also dew point hygrometers that are extremely precise; they consist of a metal surface and measure the moisture that condenses on it. Last but not least, there are hygrometer apps for smartphones (with built-in humidity sensors) or standalone sensors (with USB or wireless connectivity).
As there’s a wide variety of units for sale, choosing a hygrometer can be a daunting task. Prospective buyers should consider three major factors: requirements, specifications, and costs.
Requirements: First of all, users should decide where they’ll be using their hygrometer (home use, industrial settings). While hygrometers for home use do not have to be 100% accurate, buyers should consider if humidity will be measured in multiple rooms simultaneously or hard-to-reach areas (e.g., attic). If one wants to measure humidity outside, a home weather station is recommended instead.
Specifications: When buying a hygrometer, users should understand that accuracy is critical. When it comes to digital units, +/- RH ratings should be considered. Factors such as power source, user interface, data logging, and access to historical data are also important. As mentioned above, if one wants to monitor several places simultaneously, a hygrometer that can connect to different sensors as one system is needed. Last but not least, updates and alerts that allow users to monitor humidity remotely are also beneficial.
Total costs: When it comes to meters, more precise instruments are often more costly. Note that humidity measurers designed for industrial use may need additional NIST Traceable certification.
Hygrometers are excellent scientific instruments. Given that hygrometers have a wide variety of applications, it’s no surprise there are a plethora of units for sale. Unfortunately, buying a hygrometer can be a challenging task. Based on different parameters and user reviews, here are the best humidity meters for sale. Note that thermo-hygrometers are a popular alternative.
ThermoPro TP55 Digital Hygrometer – Indoor Thermometer, Humidity Gauge with Jumbo Touchscreen, and Backlight Temperature Humidity Monitor is one of the most precise units on the market. Note that this product has both humidity and temperature sensors. The unit is equipped with professional-grade sensors and has high accuracy (2-3% RH and +/-1°F/°C), with readings that update every ten seconds. This meter also provides humidity trends and records (24 hours/all-time/high and low records) and shows temperature changes in both °F and °C. With its large touchscreen display with a backlight (that turns off after 15 seconds), this unit is an attractive humidity meter.
AcuRite 01083 Indoor Thermometer & Hygrometer with Humidity Gauge & Pro Accuracy Calibration is another great unit with strong magnetic backing. This meter measures both relative humidity from 1-99% (low/high/okay) and temperature (in °F and °C). It also ensures fast data reporting to create a comfortable living environment and better air quality (with updates every 10 seconds). Moreover, this temperature sensor and humidity gauge have an easy-to-read digital display, which makes it an attractive gift choice for both professionals and beginners.
AcuRite 01080M Pro Accuracy Temperature and Humidity Gauge with Alarms is a power meter that can measure indoor humidity (1-99%) and temperature (from -4 to 158°F or from -20 to 70°C). Note that it provides an accuracy of +/-0.5°F and +/-2% (with manual calibration options). The unit shows updates and records, including alarm notifications, to indicate when the humidity and temperature levels are outside of one’s ideal range. Note that less than 25% means a dry environment, 25-55% indicates a comfortable environment, and over 55% shows humid settings. Last but not least, this meter is compact and versatile (tabletop, wall-mountable, and magnetic back mount) – simply one of the best hygrometers for sale.
RockyMars RT36 Temperature and Humidity Meter is another great unit available on the market. The model is light and compact, which makes it a great portable hygrometer. Note that it uses three AAA batteries. It can also measure temperature from -10°C to 60°C or 14°F to 140°F, with an accuracy of +/-1.0°C or +/-2.0°F. This meter is ideal for facility maintenance, environmental monitoring, HVAC, and health care. Besides, it comes with a manual to ensure accuracy and a positive user experience.
ThermoPro TP65A – Indoor/Outdoor Thermometer, Digital Wireless Hygrometer, Temperature, and Humidity Monitor with Jumbo Backlight Touchscreen and Cold-Resistant Outdoor Thermometers (200ft/60m Range) provides users accurate humidity and temperature readings for both indoor and outdoor settings. Note that the unit can be connected to three outdoor remote sensors to assess different locations and has a waterproof outdoor thermometer sensor, which is efficient in rain or snow (as cold as -31°F/-35°C). Additionally, the unit’s indoor/outdoor wireless thermometer has a range of 200ft/60m and is capable of strong signal penetration (433 MHz). With its large display and advanced settings, this meter is ideal for a variety of applications.
Temp Stick Wireless Remote Temperature & Humidity Sensor is a sophisticated remote temperature and humidity monitor that uses two AA batteries (included). The unit allows users to check humidity (0-100%) and temperature (-40°F-140°F) levels in buildings, fridges, and hard-to-reach areas remotely. The unit supports data logging with unlimited history and sends text and email alerts to indicate an important change in temperature or humidity (note that it can alert multiple users). Moreover, the phone app and computer webpage are easy to use.
SensorPush Wireless Thermometer/Hygrometer for iPhone/Android – Humidity & Temperature Smart Sensor with Alerts provides reliable measurements via Swiss-made sensing components. The unit has -40°C-60°C (-40°F-140°F) temperature and 0-100% humidity ranges. Note that this meter is a powerful model (with a range of 325 feet), which makes it ideal for tracking humidity in hard-to-reach areas, such as guitar cases, attics, and basements. Besides, the app is easy to navigate and provides unlimited in-app data storage (compatible with iOS 8+, Android 5.0+, and Bluetooth 4.0+/LE).
Ambient Weather WS-3000-X5 Wireless Thermo-Hygrometer with Logging, Graphing, Alarming, Radio Controlled Clock with 5 Remote Sensors is an advanced thermo-hygrometer with wonderful interface settings. The unit has a TFT color display that allows the graphing and monitoring of various parameters, such as temperature, humidity, dew point, and heat index (note that it allows users to monitor up to eight channels at the same time). The clock included automatically synchronizes the time several times a day and adjusts for daylight savings (it includes 24 time zones throughout the world). The unit also allows users to set high and low alarms (both audible and visual) for any of the measured parameters. Last but not least, this meter includes PC software for advanced data analysis, console programming, and easy data extraction from the optional micro-SD card.
Extech Digit Thermometer is a great unit that displays relative humidity, temperature, and dew point. Note that this model recalls minimum and maximum readings and provides visual and audible warnings. Additionally, the meter has a remote probe that can extend on an 18-inch cable, which makes it ideal for measurements behind walls and hard-to-reach areas. Additional NIST Traceable certification is available, allowing the monitoring of environmental conditions in laboratories, storage areas, and manufacturing assembly places.
Cigar Oasis Analog Hygrometer by Western Humidor is a precise analog hygrometer. Note that the unit’s humidity sensor has an accuracy of +/-1%. Besides, the unit is user recalibrate-able. With a scratch and fog-resistant glass face, an aluminum case, and a secure magnetic mount, this hygrometer is highly valuable, particularly in the cigar industry.
Hygrometers are invaluable instruments in numerous settings. They are ideal for weather monitoring, home use, automated manufacturing processes, monitoring environments in museums and training centers, plant nurseries, and product research. Note that some popular industrial applications include polyethylene production, liquefaction of natural gas, medical equipment, food packaging, coatings industry, and incubators. Small and portable devices are ideal for field work, while decorative models are perfect for home use.
Portable, freestanding, wall, and magnetic units all need proper calibration, maintenance, and storage conditions to ensure accurate and long use. To provide an example, users should realize that exposure to high relative humidity may create an offset in readings. Calibration and period re-calibration are also essential to guarantee accurate measurements and readings.
Hygrometers are invaluable scientific instruments used in a variety of applications to measure humidity levels. Measuring humidity levels in the air, soil, and enclosed space is essential to guarantee positive health outcomes and comfort, proper storage conditions, and effective manufacturing processes. Given their diverse applications, it’s no surprise hygrometers designed for home uses are increasing in popularity. Note that some units measure humidity in a single spot, while others come with different sensors to facilitate monitoring in various areas.
Here we should note that although hygrometers come in different shapes and sizes, digital hygrometers and apps are preferred as they provide automatic readings, updates, and alerts to help users track humidity. That being said, prospective buyers should consider three major factors: requirements, specifications, and total costs. Accuracy, data logging, history records, and design are major factors to consider. Units that measure both humidity and temperature are also highly popular.
In behavioral neuroscience, the Open Field Test (OFT) remains one of the most widely used assays to evaluate rodent models of affect, cognition, and motivation. It provides a non-invasive framework for examining how animals respond to novelty, stress, and pharmacological or environmental manipulations. Among the test’s core metrics, the percentage of time spent in the center zone offers a uniquely normalized and sensitive measure of an animal’s emotional reactivity and willingness to engage with a potentially risky environment.
This metric is calculated as the proportion of time spent in the central area of the arena—typically the inner 25%—relative to the entire session duration. By normalizing this value, researchers gain a behaviorally informative variable that is resilient to fluctuations in session length or overall movement levels. This makes it especially valuable in comparative analyses, longitudinal monitoring, and cross-model validation.
Unlike raw center duration, which can be affected by trial design inconsistencies, the percentage-based measure enables clearer comparisons across animals, treatments, and conditions. It plays a key role in identifying trait anxiety, avoidance behavior, risk-taking tendencies, and environmental adaptation, making it indispensable in both basic and translational research contexts.
Whereas simple center duration provides absolute time, the percentage-based metric introduces greater interpretability and reproducibility, especially when comparing different animal models, treatment conditions, or experimental setups. It is particularly effective for quantifying avoidance behaviors, risk assessment strategies, and trait anxiety profiles in both acute and longitudinal designs.
This metric reflects the relative amount of time an animal chooses to spend in the open, exposed portion of the arena—typically defined as the inner 25% of a square or circular enclosure. Because rodents innately prefer the periphery (thigmotaxis), time in the center is inversely associated with anxiety-like behavior. As such, this percentage is considered a sensitive, normalized index of:
Critically, because this metric is normalized by session duration, it accommodates variability in activity levels or testing conditions. This makes it especially suitable for comparing across individuals, treatment groups, or timepoints in longitudinal studies.
A high percentage of center time indicates reduced anxiety, increased novelty-seeking, or pharmacological modulation (e.g., anxiolysis). Conversely, a low percentage suggests emotional inhibition, behavioral avoidance, or contextual hypervigilance. reduced anxiety, increased novelty-seeking, or pharmacological modulation (e.g., anxiolysis). Conversely, a low percentage suggests emotional inhibition, behavioral avoidance, or contextual hypervigilance.
The percentage of center time is one of the most direct, unconditioned readouts of anxiety-like behavior in rodents. It is frequently reduced in models of PTSD, chronic stress, or early-life adversity, where animals exhibit persistent avoidance of the center due to heightened emotional reactivity. This metric can also distinguish between acute anxiety responses and enduring trait anxiety, especially in longitudinal or developmental studies. Its normalized nature makes it ideal for comparing across cohorts with variable locomotor profiles, helping researchers detect true affective changes rather than activity-based confounds.
Rodents that spend more time in the center zone typically exhibit broader and more flexible exploration strategies. This behavior reflects not only reduced anxiety but also cognitive engagement and environmental curiosity. High center percentage is associated with robust spatial learning, attentional scanning, and memory encoding functions, supported by coordinated activation in the prefrontal cortex, hippocampus, and basal forebrain. In contrast, reduced center engagement may signal spatial rigidity, attentional narrowing, or cognitive withdrawal, particularly in models of neurodegeneration or aging.
The open field test remains one of the most widely accepted platforms for testing anxiolytic and psychotropic drugs. The percentage of center time reliably increases following administration of anxiolytic agents such as benzodiazepines, SSRIs, and GABA-A receptor agonists. This metric serves as a sensitive and reproducible endpoint in preclinical dose-finding studies, mechanistic pharmacology, and compound screening pipelines. It also aids in differentiating true anxiolytic effects from sedation or motor suppression by integrating with other behavioral parameters like distance traveled and entry count (Prut & Belzung, 2003).
Sex-based differences in emotional regulation often manifest in open field behavior, with female rodents generally exhibiting higher variability in center zone metrics due to hormonal cycling. For example, estrogen has been shown to facilitate exploratory behavior and increase center occupancy, while progesterone and stress-induced corticosterone often reduce it. Studies involving gonadectomy, hormone replacement, or sex-specific genetic knockouts use this metric to quantify the impact of endocrine factors on anxiety and exploratory behavior. As such, it remains a vital tool for dissecting sex-dependent neurobehavioral dynamics.
The percentage of center time is one of the most direct, unconditioned readouts of anxiety-like behavior in rodents. It is frequently reduced in models of PTSD, chronic stress, or early-life adversity. Because it is normalized, this metric is especially helpful for distinguishing between genuine avoidance and low general activity.
Environmental Control: Uniformity in environmental conditions is essential. Lighting should be evenly diffused to avoid shadow bias, and noise should be minimized to prevent stress-induced variability. The arena must be cleaned between trials using odor-neutral solutions to eliminate scent trails or pheromone cues that may affect zone preference. Any variation in these conditions can introduce systematic bias in center zone behavior. Use consistent definitions of the center zone (commonly 25% of total area) to allow valid comparisons. Software-based segmentation enhances spatial precision.
Evaluating how center time evolves across the duration of a session—divided into early, middle, and late thirds—provides insight into behavioral transitions and adaptive responses. Animals may begin by avoiding the center, only to gradually increase center time as they habituate to the environment. Conversely, persistently low center time across the session can signal prolonged anxiety, fear generalization, or a trait-like avoidance phenotype.
To validate the significance of center time percentage, it should be examined alongside results from other anxiety-related tests such as the Elevated Plus Maze, Light-Dark Box, or Novelty Suppressed Feeding. Concordance across paradigms supports the reliability of center time as a trait marker, while discordance may indicate task-specific reactivity or behavioral dissociation.
When paired with high-resolution scoring of behavioral events such as rearing, grooming, defecation, or immobility, center time offers a richer view of the animal’s internal state. For example, an animal that spends substantial time in the center while grooming may be coping with mild stress, while another that remains immobile in the periphery may be experiencing more severe anxiety. Microstructure analysis aids in decoding the complexity behind spatial behavior.
Animals naturally vary in their exploratory style. By analyzing percentage of center time across subjects, researchers can identify behavioral subgroups—such as consistently bold individuals who frequently explore the center versus cautious animals that remain along the periphery. These classifications can be used to examine predictors of drug response, resilience to stress, or vulnerability to neuropsychiatric disorders.
In studies with large cohorts or multiple behavioral variables, machine learning techniques such as hierarchical clustering or principal component analysis can incorporate center time percentage to discover novel phenotypic groupings. These data-driven approaches help uncover latent dimensions of behavior that may not be visible through univariate analyses alone.
Total locomotion helps contextualize center time. Low percentage values in animals with minimal movement may reflect sedation or fatigue, while similar values in high-mobility subjects suggest deliberate avoidance. This metric helps distinguish emotional versus motor causes of low center engagement.
This measure indicates how often the animal initiates exploration of the center zone. When combined with percentage of time, it differentiates between frequent but brief visits (indicative of anxiety or impulsivity) versus fewer but sustained center engagements (suggesting comfort and behavioral confidence).
The delay before the first center entry reflects initial threat appraisal. Longer latencies may be associated with heightened fear or low motivation, while shorter latencies are typically linked to exploratory drive or low anxiety.
Time spent hugging the walls offers a spatial counterbalance to center metrics. High thigmotaxis and low center time jointly support an interpretation of strong avoidance behavior. This inverse relationship helps triangulate affective and motivational states.
By expressing center zone activity as a proportion of total trial time, researchers gain a metric that is resistant to session variability and more readily comparable across time, treatment, and model conditions. This normalized measure enhances reproducibility and statistical power, particularly in multi-cohort or cross-laboratory designs.
For experimental designs aimed at assessing anxiety, exploratory strategy, or affective state, the percentage of time spent in the center offers one of the most robust and interpretable measures available in the Open Field Test.
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